I don't know of any but there's a link you could get them to click on www.sourpatch.org which will, I am told, opens a gay porn site which they won't be able to close without crashing their pc.
A read a great book where a guy wrote about all his experiences winding up Nigerian scammers. It has some great ideas....
http://www.amazon.co.uk/Greetings-Jesus-Name-S cambaiter-Letters/dp/1905128088/ref=sr_1_1?ie= UTF8&s=books&qid=1206795167&sr=8-1
He got thyese scammers to tattoo themselves, change religions., all sorts of things!