Why won't my texture render? I made a mug as my first blender artwork, and it looks pretty good. I unwrapped it using smart unwrap, and it still looks good. I exported the UV layout to GIMP and painted it, then exported it back to a png. Now I can load the image into the UV editor and it all looks fine, but it won't render on my 3d object. Any ideas? 

(Let me know what else you need since I'm sure you're going to ask for screenshots, but I'm not sure what screenshots you need.)

The texture does show up in texture mode, but when I go to view it as rendered it disappears. Additionally in texture mode it shows up very dull and the specular mapping isn't working properly. Eventually I'd like to bake in the specular and diffuse settings so I can export the UV map and object as an FBX for Unity.

Finally, I realized the thing is not retaining the grouping when I export (it exports the torus and the cylinder as separate pieces) and that the UV unwrap is in the wrong place. The words on the side of the mug are cut off.
Do you know how to set up material nodes?
(Assuming your in cycles)
You need to use an texture node in your material setup: