my mtb is right around 20.25 lbs, and is built up as follows:

frame: 1995ish gary fisher cronus w/ matching rigid fork
headset: chris king pink "pretty and strong"
stem: bontrager race x lite
bars: bontrager race xxx lite flat
brake levers: avid speed dial 7
front brake: avid single digit sl
rear brake: avid single digit 7
bb: truvativ gigapipe sl (this thing weighs a ton)
cranks: bontrager ss
front wheel: bontrager race x lite
rear wheel: white industries eno & bontrager mustang
tires: irc mibro
pedals: eggbeater 2ti

if i switched out to one of those Pace forks or something i could probably drop a pound or so, but those forks are all too long. throws the handling way off.