I thought it would be handy to create a list of downloadable free and open source software, particularly software that has a productive purpose and replaces the more popular paid software. I will not include any software that has paid licenses or paid versions which add features that personal users might want, it will not include operating systems since there are way too many, and it will not include software that is useless for Windows-only systems. It does include software that can use paid services, but isn't a significant part of the software. If anyone wants to add to this list, just post it and I'll add it, assuming it fits in properly.
This list isn't for games, since games have a very different purpose from most other software. If I do a list for games, it will be in the PC gaming forum.

* = Free, proprietary
** = Open Source

Audio editor**: Audacity
Defragmenter**: JkDefrag
Defragmenter**: UltraDefrag
Email notifier*: ePrompter
Email client**: Thunderbird
File compression**: 7-Zip
FTP client**: FileZilla
Image editor**: Gimp
IM client (multi)**: Miranda IM
Media converter*: SUPER
Media editor/converter**: VirtualDub
Media player**: VLC
Partition manager**: GParted
Podcast receiver**: Juice
Spyware remover*: Spybot - Search And Destroy
Voice chat**: Mumble
VoIP phone*: Gizmo5
VoIP phone*: Skype
Word processor**: OpenOffice
Web browser**: Firefox