Wow, look at me with my first non-Drupal related post. ;)
I recently upgraded to Leopard and since then, Mail.app hasn't worked properly with my crappy e-mail provider, so I decided to give Thunderbird another shot. I like a lot of features in Thunderbird, including the fact that it's open source, it has useful extensions like Enigmail, and it doesn't take forever and a week to retrieve my list of new messages like Mail.app does (or did under Tiger, anyway).
Of course, the one major problem Thunderbird has is that it sometimes takes forever to load a message body. Or at least it did, until I literally Googled for thunderbird takes forever to load a message body, and came across this gem in the comments of a lifehacker story: