VI
Use Terminal’s vi as default text editor http://www.macosxhints.com/article.php?story=20080305012955463
DTerm
DTerm offers a command line anywhere and everywhere http://www.decimus.net/dterm.php
SIMBL
Smart InputManager Bundle Loader Problem: Some applications do about 90% of what I want. Solution: Develop my own applications. Better Solution: Patch the application myself…
http://www.culater.net/software/SIMBL/SIMBL.php
Visor
Visor provides a systemwide terminal window accessible via a hotkey, much like the consoles found in games such as Quake.
http://code.google.com/p/blacktree-visor/