The last thing I learned in 2008 was the making of a 3D Tux image. You too can find a beautiful tutorial at the <crystalxp.net>. There is tutorial for the photoshop as well as for the GIMP. But the GIMP tutorial is in French.
I made it with GIMP (but I don’t know French 🙂 ).
Here is the final thing I made. This need many modifications. Comments invited.