I guess mail is the most important invention since sliced bread. And I really care about mails. I have already tested Postbox and MailPlane so far. But both of them weren't the perfect fit for me. Postbox was not very "Mac OS X"-ish and MailPlane could, of course, only handle my GMail accounts. And then SparrowApp made it to the Mac AppStore.
Most modern DSLRs have a feature called "PTP" which is used to remotely control the camera via USB, make images and download them onto the computer. This feature can be pretty handy if you are into stop motion animation or time-lapse photography. iStopMotion is a software from Boinx Software which does pretty much everything you need to make such movies. Sadly Canon DSLRs are not supported by Apple, so they also don't work in iStopMotion. But there is a pretty simple way around this limitation.
Today the Mac App Store openend, and with it a great App, Twitter for Mac (formerly known as Tweetie 2) went public. The App is really great, featuring livestreams, a great UI and some cool features here and there. But I won't talk about Twitter for Mac now, because I think there is something more important to talk about.
Maybe you know this: You are sitting downstairs on the couch and then suddenly you realize that you have to do something important on your Mac upstairs. But, hey, you have your iPad right in front of you, why don't just use it? With the great VNC-client Screens from Edovia Inc. this is no longer a problem.