If you are a proud user of BBEdit, don't forget that it can help with text anywhere in the OS through the services menu.
Using Automator, you can build new services that receive selected text and replace it with some processed text. Here's an example for use with Markdown enthusiasts. I hate when I am working in TextEdit or NVAlt and I forget to prepend a list with bullets. This service fixes that.
There are a bunch of services available through BBEdit. If it is not already running, BBEdit will be launched to perform the text modification