Format Factory - a great software that allows to convert your stuff such as music or videos to a huge ammount of most and less popular formats.
BitLord - my personal favorite torrent manager & downloader, looks really nice and works fine too.
Total Commander - a great software for anyone having problems with managing their things on computer.
Daemon Tools - used for making simple disc image files and emulating virtual CD/DVD drives.
Inkscape - great vector graphics editor for Windows, Mac OS X and Linux. It's free and open source.
Crazybump - a great software (not free though, but it has a trial) used to make normal maps, specular maps, etc.
Virtual PC - it's a virtualization program for Microsoft Windows.
ComboFix - helps you to get rid of malware and other virus scums.