It's been a while, and I want to fill everyone in on what/when the next tutorial will be. This weekend is the first time I haven't had a million other projects I should be doing, so I was able to make some real progress.
The next tutorial is going to be broken into two parts (for length's sake, but Part 1 will be useful on its own).
The first part will handle loading more complex OBJ files, and loading materials from MTL files. The OBJ loader we already had only works on really, really simple OBJ files, and it won't cut it for loading most models with texture maps.
The second part will put this to better use by adding some simple lighting to the project.
Expect the whole thing before the end of the month. After the next tutorial, I plan on making a model viewer example to show what can be done.