Aquamacs
From charlesreid1
Setting Color Scheme
To set your color scheme, run M-x color-scheme-select. You should be able to click on a theme name to apply it.
Once you find one you're happy with (the midnight scheme is pretty nice), you can apply it permanently by picking Options (top menu bar) > Appearance > Adopt Face and Frame Parameters as Default.
Running GDB Through Aquamacs
One of the cool tricks you can do with emacs is to run gdb through emacs and get a split-screen with one window showing you where you're at in the source code and another window with gdb.
Here's how to get that going.
Start GDB
To get GDB started in emacs, run M-x gdb.