Chess Puzzles
Tactics Trainer from ChessBase
You are free to solve as many positions as you like. To solve stronger positions and get your own tactics ELO, visit tactics.chessbase.com.
Puzzles
If you enjoy puzzles, you might want to try your hand at solving the Eight Queens Puzzle: "The eight queens puzzle is the problem of placing eight chess queens on an 8×8 chessboard so that no two queens threaten each other; thus, a solution requires that no two queens share the same row, column, or diagonal." - Try it for a while, then check out the Wikipedia article (which has the solutions).
Here is a very complex puzzle by Ivanov.
White to play and win.
Don Ostrowski has been playing in online tournaments associated with the Wachusset Chess Club.
This position arose in his game with Brian Biglow recently. Black has just played 35... Bxg3. What is White's best continuation? To make the puzzle even more difficult, set your timer on 2 minutes [both were beginning to get low on time at that point].
Hint: At the end of the combination, White is up a queen.
And here are a few more sites for those who enjoy chess puzzles: