Blah: I nearly forgot too, there is no such thing as a dictionary that caters for every language. There's hundreds of languages in the world with tens of thousands of dialects. It'd take hundreds of years to account for them all, even if they could all be understood by the authors of the dictionaries.
There's approximately 6000-7000 languages (including dialects) thoughout the world. Yet, I couldn't imagine there being more than 22 languages spoken a considerable amount on IRC. 99.999% of the people that chat on IRC chat in one of the following 22 or so languages. I can almost guarantee you that. People in the middle of the Sahara desert, that speak some strange tongue of clicks and snaps, simply do not have computers. Below is a list of the dictionaries aspell has on their website compiled for win32, there are others that could be compiled for win32 also I think. I tried to think of languages that aren't there to no success.
Breton | Catalan | Czech | Welsh | Danish | German | Greek | English | Esperanto | Spanish | Faroese | French | Italian | Dutch | Norwegian | Polish | Portuguese | Romanian | Russian | Slovak | Swedish | Ukrainian