Tweaky is a GUI utility app for adjusting the super secret defaults preferences that are there in Twiter for Mac (Tweetie 2) but are only visible to those who bought that MacHeist bundle a while back.
The only “super secret” adjustment I care about is the ability to escape out of the Tweet compose window. And that can be done via the Terminal:
defaults write com.twitter.twitter-mac ESCClosesComposeWindow -bool true