You can find on this website a collection of free tilesets that can be used in commercial and non-commercial game projects. All the tiles are the property of their. Tilesets whose only license is GPL are specifically excluded from this collection. However, I can Lots of free 2d tiles and sprites by Hyptosis. Links to free stuff (Creative Commons-licensed and the like) that can be Tile / Map-Based Game Techniques: Handling Terrain Transitions.