I frequently find myself writing blocks of end-user facing text that are inserted into various Workflow UI components. There's no built-in spellcheck capability, so my mediocre typing accuracy has a bad habit of showing up far too often.
I'm sure there are ton of these sites, but this is the one I've been using for a few weeks now. It's a painless experience to paste in the text, get corrections and copy the results back out. I've only been using the English dictionary, but supposedly it has support for 27 languages.
http://orangoo.com/spellcheck/
A practical example: