From Florence to outlying villages

Some villages are accessible by train, but most are easier to visit by bus. They're called "hill towns" for a reason; the train often goes only to the valley below, while the bus goes much closer to the town center. By train or bus, you can see Pisa, Lucca, Siena, San Gimignano, and more. Look at Rick Steves Italy or his Florence and Tuscany books for details of exactly how to get to and from each town. Be aware that frequency of transit may be low on some routes, requiring careful planning, and that the frequency drops (or stops altogether) on Sundays. If you really want to see very small villages, a car is very helpful/necessary. Some villages have no bus service, or have just a few a day at times that are not conducive to day trips.

Priscilla, Harold provided a good overview of the options for that area. Whether it's feasible to travel to other towns will depend mostly on which towns you're planning to visit. The travel methods to each one will differ. For example, you can reach Siena by train or Bus, however Bus travel is better as that drops passengers in the middle of town rather than the bottom of the hill, and the travel time is about the same. If you could provide a few more details about your plans, it would be easier to offer more specific suggestions. Cheers!