I'm not particularly up to this techie thread, but I do want to put my vote in for Fluxbox as an alternate window manager -- it seems to be popular, and I have reluctantly started abandoning Window Maker in favor of Fluxbox. What I love about Window Maker is the ease of docking applications -- you can basically just move an application over to the dock, and that's that, permanently.

But Fluxbox has a "slit" that is not quite as easy, but is usable -- and it takes up less screen real estate, which would be important on a tablet. There are of course a lot of different "boxes", but I don't have much experience with them. I see that "openbox" actually exists among my installable applications, but I don't know how to use it. I use Fluxbox with an application called wmdrawer, which I learned about in Window Maker, but it's even more useful in Fluxbox. You click it and, accordian-like, a menu of programs scoots out for you to select from. This and things like auto-hide would be great on a tablet, it seems. Unfortunately, from some points of view, setting up Fluxbox properly is a very command-line intensive sort of operation, until you set it up to avoid that. But it is fast, flexible, and frugal with system resources, which is the key to its popularity.