I'm also going to try the ones from this page:
I'll take all the tests I can as a baseline and record them. I've only done three sessions of n-back, so it's pretty close to a baseline. I hadn't even gotten to 4-back yet and still find 3-back quite hard.
I think after doing the baselines I'm going to focus on dual n-back. Then, when I hit the inevitable plateaus, I'll switch between simple, tri, and quad n-back. I know when you get stuck in weight training that you've got to mix it up. And since I can't think of anything else, then what the hell--I'll mix it up.
I figure I'll do at least six months for the experimental phase (up to a year). And I'm going to do the best I can to avoid chunking. The task is intrinsically interesting, and the music makes for good positive reinforcement. So we'll see how long I hold up. Let's hope it's as addicting as blitz chess so that it doesn't feel like a chore.