It depends on your possible role.
It sounds like you would be on the business, or operations side, not the development side, though.
There are many ways you can add to a start-up, it depends heavily on what they have in place and what holes they still have.
For example, if you happen to have a good understanding of the automotive industry, with connections to dealerships, then you may be able to help with a distribution chain.
If you have been doing Youtube videos for years, then you may want to look at trying to do something for http://current.com, which is the web side of CurrentTV, as that would give you a free way to see if you can get some airtime for your product.
It will depend on your experiences, connections and imagination. You can figure out what they need, that they don't realize they need, but then you have to show your salesmanship by selling the fact that they need you to them.