Just a short update: I updated my extension and uploaded it to the Google Extensions sites. You can find it at http://tinyurl.com/SOExtension (Chrome version 4 and above and a StackOverflow profile required).
Version 1.2.0 now supports Meta.StackOverflow, utilizes the latest jQuery library (1.4.1) and fixes an annoying bug - all those by requests from users (see comments on that page).
I'm considering a future version that will alert you to a reputation change automatically. In the meantime, keep the comments and requests coming - I'm having fun
Update: just got a 'stamp of approval' from Jon Skeet, the leading StackOverflow-er . It was due to Jon's and Dan's requests that I've added Meta support. See the announcement here: http://meta.stackoverflow.com/questions/37731/stackoverflow-chrome-extension
Update 2: Just updated to version 1.2.1: The options page now includes instruction on where to find your Profile ID - thanks for the suggestion Sasha!