If you're in Peru chances are you're going to want to travel to other countries nearby. Keep in mind that you'll probably end up paying visa / entry fees. Here's some info on what those are.
- BootsNAll: they tell you how to legally get out of paying the fees.
- Matador Network: Guide for Americans
- Project Visa: (Their info for Peru is wrong: says you can only get 90 days when it was changed to up to 183 days quite a while ago. Be sure to double check their info.)
- South American Living: info about Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru, and Uruguay.
- Wikipedia World Wide Guide: has to be included in the list