While I finish up the spectral undead, I'm also working on mummies. Originally, I figured a mummy would just be a specific variant of the corporeal undead, but then I had a few ideas about what could make them distinct as an entire "class" of undead, with a progression of powers and behaviors uniquely their own.
The problem, though, is that there's only one mummy-like undead listed in OD&D. So I have to come up with a bunch of names for greater and lesser varieties of mummies. That may delay me a bit.
If anyone knows of some legendary mummy-like creatures, that might help. Please, no unique fictional creations.