CodingBat

CodingBat is a website devoted to teaching Java and Python! The great thing about it is that it's not a tutorial or a collection of tutorials, but a collection of practice problems, which is even better. The site will keep track of the problems you've completed if you create a account (which is free).

Topics covered include Strings, arrays, logic, and recursion. I found it quite valuable when learning Java syntax. After all, as the site says, "Talent is but a rumor, but practice works."