http://www.travel-photographs.net/peru-photos/
Study Spanish - An excellent site which covers a bunch of different grammatical topics.
Spanish Language & Culture (Colby College) - Created for college students, you will find many useful grammar exercises here, although some are more advanced!
Spanish Grammar Exercises - Another useful site full of grammar exercises from Trinity University in Texas.
Verb Conjugations - Type in a verb and this site will give you complete conjugations in every tense we've ever learned (and then some!).
Spanish Flashcards - Practice quizzes for grammar and vocabulary. (All the links in blue are free. You have to have a paid membership for the red links.)