Originally Posted by ofofhy
Wasn't that a Simpson's episode?
And a darn good one at that.
As to the original question, I think everyone's missing one of the easiest and most cost effective options-ditching the infernal adjustable stem, if it is still on your bike. Switching that for any basic alloy stem will yield significant weight savings, more so than anything else previously mentioned.
As Trogon said, most of what you mentioned isn't all that cost effective. The real weight savings are to be had with more expensive options, which I wouldn't consider all that wise in light of the bike in question. One other option would be lighter tires/tubes, as Chuck mentioned.