Yeah, so i found out you can summon these guys after you kill them with the thrall zombie spell, it's nice to have them around:
http://www.youtube.com/watch?v=Qbpe6Fm_ndQ

Actually there are far more powerful dead thralls out there you just need to invest the time and energy to make sure you don't loose them.

Archmage Savos Aren
Sebastian Lort
Orchendor

All make for extremely powerful dead thrall companions. There are others but I forgot their names due to me not using them too much.