Nice intro to Mercurial, a distributed source code control system. If you do ANY type of coding, even HTML, and you use no source code control system, then you're an idiot (or just very uninformed). Mercurial is free and seems very easy and straightforward to install and use. It also appears to be very powerful. I will look into it for my personal projects.
I use MobileMe to store all my email, but I want to maintain my own email address as far as others are concerned. This tip allows all email I send from my iPhone to correctly appear as if they went sent from my @kirsch.com.mx address and not my @me.com address.