I''ve had a lot of success using textures from www.freetextures.com; admittedly, I tend to use polygon rendering so square textures are immediately appropriate, but its not hard to rotate/resize tiles in an art package if you want diamond shaped tiles with a colour keyed background suitable for blitting. Of course you get some distortion because of rotating/resizing, but it doesn''t seem to matter too much in games. The alternative is to render a big scene and cut tiles out of it!