USEFUL SOFTWARE | Free, Open Source, Commercial

[Paddy™]

Have you checked out Backloggery, IIPEE?

If you're like me and enjoy having applications which aren't glued to the system registry, check out PortableApps.com. If any of my software suggestions below have a portable option, either from PortableApps.com or their own portable build, I'll include a P next to the OS.

Spoiler below!

AIMP | Free | Windows | P
An audio player I discovered after Winamp disappeared. I've never looked back, the feature list is insane.

Areca Backup | Free/Open Source | Windows/Linux | P
An intuitive and lightweight file backup tool.

CamStudio | Free | Windows | P
A basic screen recording utility, supports AVI and SWF formats. Unfortunately it doesn't seem to work in fullscreen applications like games.

CCleaner | Free | Windows | P
A basic system cleaner, for removal of junk, temp files and obsolete registry entries. If you want to expand the cleaning options, you can use CCEnhancer.

CDBurnerXP | Free | Windows | P
A free but very dependable CD/DVD/Blu-ray/HD-DVD burner. It supports audio discs, data discs and image creation/burning.

Cheat Engine | Free/Open Source | Windows | P
A tool for cheating in games using memory hacks. Even beginners can usually create a few working cheats for basic things pretty quickly, like infinite ammo or money.

Comodo Internet Security | Free | Windows
A free suite of security applications, including a firewall, anti-virus, system registry protection and sandbox for testing executables. Some of the components can be installed independently (for instance, if you just want a firewall).

Comodo Dragon | Free | Windows | P
A security/privacy-conscious build of Chrome.

Comodo IceDragon | Free | Windows | P
A security/privacy-conscious build of Firefox.

CookTimer | Free/Open Source | Windows | P
A simple timer with an audio alert.

Defraggler | Free | Windows | P
A straight-forward, on-demand hard disk defragmentation tool.

Driver Fusion | Free | Windows
A tool for cleaning up the traces of old GPU drivers during an upgrade. The free version leaves one or two registry entries behind, but it works fine.

DShutdown | Free | Windows | P
A simple tool to shutdown your PC (or another one on the network) under a variety of different circumstances.

FileASSASSIN | Free | Windows | P
A single-purpose tool to "unlock" files which are locked by the operating system, allowing you to delete or move them again. Every tried to delete a file but it was "in use" and you couldn't figure out why?

Free Audio Converter (fre:ac) | Free/Open Source | Windows/Mac/Linux | P
One of the best CD-ripping and audio conversion tools out there.

Free Download Manager | Free | Windows | P
One of the easiest to use and least-intrusive download managers, like FlashGet used to be.

Genymotion | Free | Windows
Requires free registration. This is an Android phone/tablet emulator for Windows. It uses VirtualBox and includes it in the download. If you want to get the Google Play Store to work, follow the instructions in this video. I prefer Genymotion over Bluestacks, because Bluestacks seems to embed itself deeply into your system and runs half a dozen services in the background. Very bloated and intrusive.

GifCam | Free | Windows | P
This tiny tool is the easiest way to create/capture GIF animations I've found. It includes resizing and optimisation settings.

GXSCC | Free | Windows | P
This little player plays back MIDIs in such a way that they sound like oldschool chiptune songs.

Handbrake | Free/Open Source | Windows/Mac/Linux
A very powerful video transcoder/converter.

KompoZer | Free/Open Source | Windows/Mac/Linux | P
A simple WYSIWYG web page designer.

LMMS | Free | Windows/Mac/Linux
A free alternative to programs like FL Studio. Supports VST instruments, piano roll, and effects mixing.

Malwarebytes' Anti-Malware Free | Free | Windows
A free on-demand malware/virus scanner.

Maxthon | Free | Windows/Mac/Linux | P
A fast and clean web browser supporting both the Trident and Webkit layout engines. Supports extensions/add-ons.

Media Player Classic - Black Edition (MPC - BE) | Free/Open Source | Windows | P
A video player with a clean interface, supporting DVDs as well as pretty much any format of video or audio file.

Mp3tag | Free | Windows/Mac
A very powerful audio file tagging program.

MuseScore | Free/Open Source | Windows/Mac/Linux | P
A very powerful score writer, which now includes support for guitars. Can import other common formats, including Guitar Pro files. A free alternative to programs like Finale and Sibelius.

PeerBlock | Free/Open Source | Windows | P
A simple program which blocks access to/from your PC using IP blocklist filters. You can get free filter subscriptions here, but many of the more comprehensive lists require a paid subscription ($9.99 per year).

Process Hacker | Free/Open Source | Windows | P
A replacement for the standard Windows Task Manager. One of the best I've found to date.

qBittorrent | Free/Open Source | Windows/Mac/Linux | P
A simple, non-intrusive and lightweight BitTorrent client.

Recuva | Free | Windows | P
File recovery/undeletion.

ReNamer | Free | Windows | P
A batch file renaming utility, supporting dozens of different rulesets.

RSSOwl | Free | Windows/Mac/Linux | P
An Atom/RSS feed downloader. Supports filters. Note: if you want the program to be truly portable, you'll need to change the config file so that the settings are saved in the program directory.

theRenamer | Free | Windows
This program will rename and sort your downloaded TV shows and movies according to user-defined rules.

ShadowCopy | Free | Windows
This program allows you to copy files which are currently in use by the operating system. Very handy if you want to make system backups but don't want to close down all of your programs first. It uses Windows' Volume Shadow Copy service to achieve this.

SharpKeys | Free/Open Source | Windows
This small tool allows you to change the function of any key on your keyboard. You can swap keys around or disable them entirely. It works by adding the change to the system registry (a reboot will be needed for the changes to take effect).

Speccy | Free | Windows | P
A lightweight system hardware information tool. Includes temp readings.

Spybot - Search & Destroy | Free | Windows | P
An on-demand anti-malware scanner, secure file shredder, browser "immunizer" and system registry protector.

SpywarerBlaster | Free | Windows
This program adds lists of undesirable (i.e. malware-ridden) URLs to your browser's restricted zones and the system's hosts file (redirected to 127.0.0.1).

Sumatra PDF | Free | Windows | P
An extremely lightweight and fast PDF reader. It also supports ePub, MOBI, CHM, XPS, DjVu, CBZ and CBR files.

SUMo | Free | Windows | P
This program checks your system for executables and compares them to an online database to see if there are new versions/updates for the programs. WARNING: the standard installer comes bundled with lots of garbage. If you download the portable version you can avoid this.

Tor Browser Bundle | Free/Open Source | Windows/Mac/Linux | P
Anonymous web browsing using a modified version of Firefox. Gain access to the dark net/deep web, or visit sites which are blocked by your ISP.

FileHippo App Manager (Previously "Update Checker") | Free | Windows | P
Checks your system for installed programs and published a list of updates when available. Only handles software which is offered on FileHippo.com. To make it portable, install it then simply move the main .exe file to wherever you want, then uninstall.

VirtualBox | Free/Open Source | Windows/Mac/Linux
Desktop virtualisation suite. Useful for testing operating systems in a virtual environment or just having access to more than one O/S without needing to dual boot.

Vivaldi | Free | Windows/Mac/Linux | P
A new web browser (currently only a technical preview) from the original developers of Opera. I'm very interested to see where this one goes. To install it as a portable app, select the "standalone" option when you run the installer.

Volume2 (Volume²) | Free | Windows | P
A replacement for the standard Windows volume control in the system tray. Supports hotkeys and mouse-wheel actions.

Windows System Control Center (WSCC) | Free | Windows | P
This is a downloader/updater for two huge suites of free programs, NirSoft Utilities and Sysinternals. Each suite is filled with extremely useful tools for managing and tweaking your system, including AutoRuns and BlueScreenView.

That should be enough for one post haha.