I like the challenges part because many "scratch your own itch" startup ideas are narrowly focused on very few social or entertainment areas that younger startup founders are familiar with. Startups often lack real problems to solve in my view.

You should try to get companies to sign up and describe the really tough problems they have. Not the every day cruft that they might like to offload onto students. I think you should avoid the kind of mood that dominates sites like elance or mechanical turk or all the Q&A sites. It's so horribly depressing there.

The challenges should be BIG. That doesn't mean the ideas/solutions have to be big. Big challenges to incentivise small experimental approaches. That's what I would love to see.

Good luck.