Mine are:
Emesene - MSN messenger client Qalculate! - Advanced calculator with history and variable substitution Frostwire or GTK-Gnutella - File sharing Thunderbird - Email (if you set it up properly, you can share your mail and settings with your windows install) Firefox - Web Browser (you can also share your bookmarks/history/settings with your windows install) AcetoneISO - Easily mount ISO files MOC Player - CLI-only music player with playlists VLC - Video and Music Player, supports lots of formats Steamtuner and Streamripper - Rips your favorite radio stations into individual song files Gwenview - Image Viewer Yakuake - Summon your terminal quickly Hardinfo - Information about your computer (Linux equivalent of AIDA32 or EVEREST) Ubuntu Tweak - Tweak your ubuntu! Filezilla - FTP client Quanta - HTML and PHP editor suite with project management K9copy - Copy and Rip your DVDs fusion-icon - Easily toggle and control your compiz fusion settings LBreakout2 - A fun block breaking game Audacity - Audio recorder and editor HTop - A process viewer for the command line
Nearly all of them are available to Ubuntu, a couple might require extra repos to be added. If you're on a different distro, then you can search for them using your package manager, or failing that, compile them from source.
chntpw - Peter Nordahl's famous Offline NT Password and Registry Editor (easy) -- also available as a bootable utility ophcrack - Windows Password cracking tool (easy) -- also available as a LiveCD aircrack-ng - WEP encryption cracking suite (this one has a learning curve)
It's quite easy to turn a thumbdrive or portable hard drive into a portable desktop environment used for entertainment and system recovery, as well as a means to gain intrusion into PC's and networks (sometimes its even necessary to do even for legitimate purposes).
In fact that's pretty much what I did with the 120GB portable hard drive (Freeagent Go) i purchased 2 years ago. Repartitioned it with a 10GB linux partition, 1GB swap, and the remainder an NTFS storage partition. It's been the most useful tool in my computer repair arsenal (even slightly outweighting the trusty #2 phillips screwdriver)
I'm always looking for more hacker tools that I can learn and use for practical applications.
Battle for Wesnoth - A turn-based strategy game with downloadable campaigns (ubuntu package name: wesnoth-all)
PCSX - A playstation 1 emulator
ZSNES - Super Nintendo Emulator
vbaexpress - Gameboy Advance Emulator
Sauerbraten - First Person Shooter
Nexuiz - First Person Shooter
Alien Arena - First Person Shooter
Tremulous - First Person Shooter
There was a roguelike (dungeon crawler) adventure game I used to have before called 'adom' though I dont know how it ranks in comparison to other roguelikes since I thats the only one I played though you die a lot the first few times you play it since theres a few rules in the game which are not so intuitive.