I wouldn't even attempt to create a forum (especially one with the intention to compete with vb lol) you would be wasting your time. Now, you don't need to think of a script that has never been done before, just research what the most popular scripts are right now and what your competitors are. I think image hosting/file upload scripts are very in at the moment and from the ones i've see they are all very similar. I think if you created a script within this market and promoted it effectivly you would definitly sell a few copies with ease! Just undercut your competitors price and include a few extra tidbits