It's a great add-on.
A couple of suggestions for future versions:
- Add rel=nofollow to all the twitter links -- if it doesn't already have no-follow, then nofollow it.
- Please don't change it to open links in a new window... that is bad for usability because different browsers handle that behavior differently. Some browsers will unexpectedly open a new tab 25 tabs away from the original tab if you set links to open in a new window