I had a tablet for a couple of years (Lenovo). My experience was that after the cool factor wore off, I ended up using the tablet for only one application -- giving presentations and being able to ink up the page during the talk. That's a pretty strong use, and I still keep the tablet around for those uses. But I've moved away from it these days and back to a more heavy-duty laptop with a larger screen, faster CPU, etc. It was just too slow (optimized for long battery life, so slower hard drive, slower CPU) for heavy lifting.

But as long as you're enjoying yours, try "crayon physics" -- it's a really fun game that benefits from having a tablet. Also, artrage is a pretty nifty drawing/painting program that really works well with a tablet. And, of course, PDFAnnotator, if you ever have to review papers.