A while ago, Derek Powazek proposed an idea for a mini Mail window based on the functionality of iTunes' mini option; hit the best fit button - the green one - in iTunes to get an idea, or simply check out Derek's post for an actual screenshot mockup of the concept. Fortunately, John Gruber just caught that OliveToast software literally ran with the concept, releasing - to my absolute delight - a MiniMail plug-in for Apple Mail.
As you can see, MiniMail allows users to simply hit Mail's best fit button (or choosing Window > Zoom) to condense it to a 'just what you need' view, offering a customizable preview area and three menu buttons for performing a healthy set of operations. Fortunately, keyboard shortcuts still work fine as well, so ???-n will create a new message. Even using the arrow keys works for moving back and forth in the message list, and thankfully, the list of mailboxes is customizable for this view as well so you can see just what you need.
After a few minutes of tinkering with the demo while writing this post, I'm happy to say that the receipt for my $9 license just arrived. MiniMail rocks, and I'm so glad someone brought Powazek's concept to life, as this is the perfect compromise that I've been looking for between constantly hiding and showing Mail while still making it easy to do basic things in it on the fly. Thanks, OliveToast software.