If you’re fundraising a lot of money, look for a broker who will help in exchange for some equity on the back end of a success.
Does this actually happen? It does not seem like a very good idea--- the CEO will benefit a lot from making the pitch and hearing the reaction/questions, and that seems like his or her job in the pre-launch stage. If it's just a matter of making connections it seems like there are plenty of other resources rather than outsourcing to somebody else's rolodex.
Hm. Maybe I should ask on Quora--- a search there came up empty, suggesting this isn't a common scenario.