+1
Pipe/filter text to shell command or AppleScript
I like being able to select some text (or have the whole document) be filtered through arbitrary shell commands and have the result replace the selection (or document).
Customer support service by UserEcho
I've had a look at a similar problem yesterday. I'm not sure if this is even possible for a sandboxed Mac App Store app which typically can't launch other arbitrary apps or execute AppleScript.