Did You Mean?
I’m a horrible speller have always been.
I’ve noticed that Google has a much better chance at understanding what I type then OS X’s built in spell check service.
So I hacked up a service for Snow Leopard so that when you right click a word and pick “Did you mean?” it will replace that word with what Google thinks that word is.
To install it unzip the file and place it in your “/Users/YOURNAME/Library/Services” Folder
Now when you right click a miss spelled word you should see the “Did you mean?” option at the bottom. The app must support services and YMMV.