On spam protection...

[Tank Program]

Ok, so we've been talking about too much spam, people advertising, ascii art out of control, but does any actually have any ideas for ways of scanning for these things? In the source, on the server side, it's all there to just scan the text, all we need to do is stick the functions in to scan it more or less, so, can we start generating some ideas people??? (Of things we can actually implement, theoretical code samples in any language would be helpful.)