If you already use the popular word processor Tasword, you'll welcome Tas-Spell. It's a 70,000 word dictionary which can be used to check through TasWord documents, spotting errors and suggesting alternatives. You can either scan for a single word, or just go through the whole text. Obviously you can update the dictionary, adding specialised words and names which might otherwise slow things down.
Tas-Spell doesn't stop there, though. It will also provide lists of words containing unknown letters, so you can use it to help solve crosswords. Another useful trick is providing anagrams. Bear in mind that although the program contains a 70,000 word dictionary compiled with the help of Longman's, it doesn't provide definitions for the words, so it's no substitute for a printed dictionary.
Completely impractical on tape, Tas-Spell is the sort of thing which makes the Plus 3 worth while.
If your spelling isn't wot it shud be, Tas-spell will sort it out.