Turn material into image?

I have a model made of several pieces. The pieces are now Joined as one. The materials are different on the parts. Is there a way to now take the Joined object’s materials/textures and export them to a single image? Even if the image is a bunch of faces that could never be edited, it is fine, the model is complete at that point and just needs an image for bringing into other engines, such as three.js. Thanks for any info.

http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Bake
http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Bake

Thank you very much, that will come in handy. I appreciate the assistance. I put the cello model from “Junk! the Animation” into x3d and js formats, so now I can include a proper texture as well.

the cello is now textured in both online appearances

http://www.trepaning.com/3js/SEA3d/elvisJUNK.html
WASD or arrow keys to move, mouse to look, scroll middle mouse to zoom,
maybe other controls

http://www.trepaning.com/x3d/cello.html
middle mouse pan up and down,
other mouse plus alt/ctrl combinations do movements and stuff,
R resets view

1 more quick test putting Junk! cello into an environment, will do the same for all instruments later, they will make a nice walk about http://www.trepaning.com/3js/elvisWalls/celloTest.html