This is excellent except as noted previously it doesn't resize with the 'u' shortcut. If you could fix that this script would be the best thing ever!
Update: thanks to your comment on lifehacker I figured out a fix. I changed the margin-left:172px in #chrome to margin-left:0% and it works like a champ. YOU ROCK!
About Gmail - cleaner - old gmail on Apr 18 2007
About Google Reader Optimized on Nov 15 2006