Between these three tutorials, I think I can make my son some lap tees:
Made's 90 Minute Tee
Indietute's Lap Tee Pattern
Patchyapple's instructions for how to sew a lap tee neckline
P.S. My serger arrived today! I ended up getting a Brother rather than the Singer I was looking at. Now how in the heck do I use the thing?! Tips or pointers, anyone?
Update: Do you remember the book where the little train thought he could, but really he couldn't? Because that was the case with my lap tee. It was a Big. Fat. Fail. Oh well. You win some, and you lose some!