Tweeters, I've had the best luck lately going through the Surfbirds archive at http://www.surfbirds.com/phorum/list.php?f=12

Under the "newest messages" area there is a small "Search" button.

I've also had good luck just doing a Google search with the subject matter and "Tweeters" included (helps if you know the sender's name as well). Make sure you put your search string inside quotes to get a more relevant hit (eg. "Clark's Grebe" vs. Clark's Grebe will make sure you don't get a message including mention of Clark's Nutcracker etc...).

Good luck

Jason Paulios
Jpaulios at earthlink.net
Olympia, WA