Here's some great software for developers: (more detail and links to follow) Free

• MacVim - Vim for Mac
• Time Tracker - Keep track of how much time you spend on projects
• Xcode - (duh!)
• Mac Ports - Great way to get common open source utilities on your Mac
• Reducticon - Makes it easier to create iOS App Icons
• XQuartz - Provides an X11 server for your Mac. Useful if you're connecting to Unix/Linux systems.

Commercial

• Rapidweaver - One of the simplest ways of creating decently sophisticated static websites on a Mac
• AppViz 2 - Keep track of your iOS/Mac App sales
• ColorSchemer Studio - A nice little tool to help you create coherent colors