Addicted to mail.appetizer and missing it badly with Tiger? Try the similarly-free GrowlMail instead.
[robg adds: I haven't tested this one yet, but I will a bit later today -- I used Mail.Appetizer quite a lot in 10.3, and I'm anxiously awaiting the 10.4 update. This program should work in 10.3, too...]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050525014700529