Google Toolbar, G-mail Notifier, Autohide, Titlebar Tweaks, NukeAnything
, and Foxy Tunes.
Since I am a student of Japanese, I used to use the Moji extension regularly. It was a Japanese language dictionary, so you can find out what certain words or characters mean on Japanese websites. Unfortunately, it isn't compatible with 1.0PR. Guess I'll have to wait until it is.