The times I've travelled on business and tried to rent a bike have not been good experiences --mostly way too expensive with numerous hassles.
I have often considered how great it would be to have a cooperative network of bikes available for borrow. I can offer bikes for borrow for someone in Chicago area (I have a few in the 55cm range that I'd be willing to loan out).
But I am also in the Phoenix area 3/29 thru 4/4 and wondering how I'm going to arrange for a bike to use. Anything, even an old beater.