Have you ever used a three-column email application, like Thunderbird or Entourage? Ever wanted the same for Apple's own Mail? (In other words, the Preview column would appear next to the list of messages, instead of below it). Well, I found this discussion on an Ars forum, and it shows you how you can have exactly that. I tried this, and it works beutifully. I find this to be a very nice hack, and hope you will find this usefull. No need to credit me, because I just found it.
All you need to do is download and install MailWidescreen, a simple Mail plug-in. Here are the very simple installation instructions:
defaults write com.apple.mail EnableBundles -bool true
defaults write com.apple.mail BundleCompatibilityVersion 2Mac OS X Hints
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