A "free browser that allows you to have the rendering and javascript engines of IE8 beta 1, IE7, IE6, and IE5.5 on Vista and XP, as well as the installed IE in the same process."
"The MacPorts Project is an open-source community initiative to design an easy-to-use system for compiling, installing, and upgrading either command-line, X11 or Aqua based open-source software on the Mac OS X operating system."
Some very useful utilities. Service Scrubber helps you manage OS X services, Witch turns command+tab into something that can access the windows of individual applications, not just the applications themselves.