PureText is a tiny freeware utility written by Steve Miller that I find absolutely invaluable when composing emails and writing documentation. It sits quietly in your windows tray and with a single keystoke will paste the contents of the windows clipboard devoid of any formatting whatsoever.
I can't begin to count the number of times that I've wanted to copy a snippet of text from an email, document or webpage and the resulting formatiing has completely messed up the rest of my email. I'd have to open notepad, paste the text, re-select it and cut it again before I could paste it into my email - what a hassle!
With PureText, just hit Win-V, and you're done.