The Dominoes, Trominoes, and Tetrominoes ClipArt gallery offers 13 illustrations of these geometric shapes that are connected orthogonally, and have 2, 3, and 4 squares, respectively.

One Domino

A One-Sided Tetromino

A poster of five Free Tetrominoes

A poster of seven One-Sided Tetrominoes

A One-Sided Tromino

A poster of both Trominoes