I'm kinda playing the weight weenie game with my Vitus 979 right now, but I'm nearing the point of diminishing returns. Getting all the low-hanging fruit sure was fun though! C&V (especially used) weight saving stuff is cheap, I think I've been averaging $15 per 100g weight savings. Hollowpin chain, spider cassette, used Ti-railed saddle, Ti skewers, folding clinchers instead of wire-beads, ultralight tubes, alloy stem bolts, and alloy toe clips are all I've got so far. I'd like to say I've noticed a difference, but I just haven't.
I want it to weigh less than my Maine Coon cat, who is about 17lbs. This video makes it look like that should be easy!
But isn't it a bit cheating that the pedals weigh so little but the cleats, which aren't technically part of the bike, weigh more? Same with tubs. Sure you save 100g per wheel, even over folding clinchers with superlight tubes, but you've got to carry an extra tire instead of just an extra superlight tube, so you're back where you started. You're just transferring weight to the rider and kit.