Hmm I'd assume there must have been though if you are splitting the connection towards another pc as well, you are going to recieve major slowdowns on the internet.
Especailly if you have something like 28k. If you have something like 56k and split it, you'd get back on each PC about the same as having a 28k I would think.
But I do think its possible and has been done. Not sure where you could get one from though, and it depends on your internet service provider
Hope this helps