Redfoot tortoises (adult length of about 14 inches) and Russian tortoises (adult length of about 4 to 8 inches) are some of the smaller ones. All tortoises need a lot of space to roam. An outdoor pen is best. Box turtles are easier to keep, they still need a lot of space but not as much as a tortoise and they are easier to feed.
Russians are good. Males normally dont exceed about 8 inches. They make great pets! If you live in an area you can keep them outdoors for at least some of the year, that works well. I also let mine roam around the house when it is too cold for them to be outside.
Don't forget Eastern Hermans, they stay pretty small. Here's Tiki, currently at 1 1/2 yrs old. http://i7.photobucket.com/albums/y279/Stev...ds/100_0531.jpg