This is one of the best plug-in for mail in existence.
Those Microsoft Outlook users, [you really need to get a mac!] are familiar of when you receive a new email it shows a notification box saying that you have a new email and it gives you a little bit of info like some (or all) of the message, the sender, subject, and even more (i don’t remember, I stopped caring about outlook when i got a Mac). Well, people may want to see what the message is when they hear the message indicator from the mail app. That’s what this is. The version(s) for Leopard and tiger are in beta, but let me say–it ROX. No, not “rocks”, ROX”. when I get an email, i see a little box in the top right of my screen (you can click and drag the box to where you want the notification to appear) that has the sender, subject, and as much of the message as i want. you can change transparency, and in fact a lot. here is a screenshot of the preferences.
So now when I get an email, I have a little window that shows if it’s worth checking or leaving for later.
Yes, that’s it. I love it because hey, I have new mail! I’m too lazy or I’m busy so I can’t open the Mail application to check it. But what if it’s important? How should I know? Mail.appetizer. It is also incredibly customizable.