Have you written a reply to a Mail.app email some days ago, and can't remember exactly what you wrote? Don't go searching your sent folder! Just click the little circular arrow in front of the message, and your reply gets opened.
[robg adds: This is a wonderful idea ... I don't think it was in Jag; at least, I never tried it if it was!]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20031025162134799