Heh. A lot of the stuff you guys are posting are things that have viable alternatives. I thought this was supposed to be a list of stuff you "couldn't live without" not just stuff you use all the time.
Oh yeah, another program I would hate to live without is Taskbar Shuffle. It allows you to move programs around on your task bar, so they can be in the order you want. I have a very specific order I like my apps in.
If I had to go with stuff I use all the time, I'd say Photoshop, SecureCRT, FileZilla, Sftpdrive, Trillian, EverNote, Winamp, WinRar, uTorrent, MS Excel, MS Word, Google Docs, Firefox, Thunderbird, VNC, Media Player Classic, mIRC, Foxit Reader, StyleXP, Crimson Editor. (And Everquest and Macroquest.)