Under: http://wiki.openstreetmap.org/wiki/Texture_Library You can see collection of textures for OSM 3D.
For today You can use this textures with JOSM PlugIn: http://wiki.openstreetmap.org/wiki/Kendzi3d but there are some people which are also working on implementation:
osm2world and OSM3D.
The textures are often coutry specific: Maybe can somebody of you shot smoe pictures with US- typical surfaces: Doors, windows, walls, old streets?
I make seamlless textures from this pictures.
How to do pictures for texturing? There are some tutorials online. My own tutorial is unfortunatly in translation into the english: http://wiki.openstreetmap.org/wiki/Phototexturing