If you need something more than TextEdit then Textmate may do the trick. Designed especially for developers this is a powerful platform that extends Apple’s approach to operating systems into text editors.
Invert screen colors
Not many people know about his trick, but if you want to see your Mac invert its screen colors hold down Ctrl-Option-Cmd-8 on the keyboard.
Slow motion windows
Normally when you minimize a window by clicking on the yellow button it zooms to the bottom of your screen. If you’re really bored one of these days try doing it while holding down the shift button. Hey, it might not get you a girlfriend but its still cool.
Quick Look Expanded
Quicklook is one of those features that really sets a Mac apart. You don’t even have to open the file to read what’s inside. As unbelievable as it may seem there are some plugins out there that can make it even better.
Maximize screen zoom
One of the biggest complaints by new Mac users (after no right-click) is the behavior of the zoom button (the green button in the top left corner). It acts nothing like its Windows counterpart. There are several plugins out there that will force it to behave more like the maximize button in Windows.