OS X: When you copy text, sometimes — if not most times — you don't want to copy the font choice, colour and other formatting options. You just want the text. TextScrub gives that to you, taking away annoying styles and even replacing commonly-occurring words or characters you don't desire.
Although some applications support a paste without formatting shortcut (usually Command+Shift+V), many do not. If you want to scrub formatted text easily, TextScrub provides a user-definable hot key that'll get rid of any styles you don't want. It'll even remove bullet points from lists and empty lines if you'd prefer to have one big block of text.
On top of that, you can provide substitutions. For example, if you wanted to automatically scrub out your name any time it appeared in a paragraph you could tell TextScrubber to eliminate it automatically or just change it to something else. While I'd like the option to have these operations performed automatically when copying and have to press a hotkey to copy with formatting, TextScrubber solves an annoying problem with little hassle.