Entrepreneur.com came out with its list of Top 500 franchises for 2007. It is interesting to compare and contrast the different franchise opportunities. Based on the Panera research (Must be worth $4million and have $1.2million liquid to even apply) it is evident that there is alot of upside potential. (Although upside and downside are to an extent capped).
http://www.entrepreneur.com/franchise500/index.html