Even if you are not interested in starting a franchised business, there is a lot you can learn from franchises in general.
Take, for instance, the rankings put out by Entrepreneur Magazine. If you look at the top new franchises for 2008, which include Instant Tax Service, Massage Envy and Snap Fitness, you gain insight into some of the latest trends for new businesses. When looking at the top overall franchises, including 7-Eleven, Subway and Dunkin' Donuts, you can further investigate what they are doing right to be able to expand so much (and then possibly replicate their strategies).
When you research an individual franchise that is in an industry that you are considering entering, you can also gather quite a bit of market research to help you put together your business plan. For example, what is their location strategy? Do they only locate in metropolitan areas, near major freeways or in malls? What is their marketing strategy? (it is obviously working and you can learn a thing or two here) What are the capital requirements? What can you expect in sales? Margins? What processes and systems do they have in place to run efficiently? And, yes, you can find this all out. A lot of this information may be on their website and you can also ask to have additional information sent.