I did a quick search for different Twitter FireFox add-ons.  Initially I was looking for a slick way to search Twitter.  I didn't find a great selection, then I remembered that you can add custom searches to FireFox.  Here's what I did:

1. Go to http://search.twitter.com
2. Click the dropdown menu next to the upper right search box
3. Click "Add Twitter Search"
4. Thats it!

Now, I took it one step further and added a keyword shortcut for the search.  I used the keyword "t".  You can find this by selecting "Manage Search Engines" then click "edit keyword".  With this, you can now just type "t jerryjr" in the address bar and you will be on your way to quickly searching twitter.