What's the best open source utility?

[Pitbull]

I know it's been discussed tons of times (or should have been), but what do each of you think is the single best FOSS utility of ALL TIME (includes projects since abandoned)? (Oh yeah, and you can't say GNOME or the Linux kernel).

For me I would probably say Audacity or WINE

[Synergy6]

Firefox (if that counts), GIMP or GAIM. Or maybe amaroK, mplayer or xChat. Hard to say

[yoshi314]

gcc. any doubts about it? :>