Command Undead?

[Amador]

Is there a limit to the how many HD of undead you can control with this spell?

[tyckspoon]

No. It's limited by the number of spell slots you can afford to keep devoted to controlling undead (also, keep in mind you only actually get control of unintelligent undead. For anything with a brain, it's basically just 'Charm Undead.')

[Coidzor]

Also those undead are 1 2nd level spell from being someone else's pets.

It is handy for keeping pets that get bumped out of one's animate dead pool or putting them into places for passive guard duty even after the spell wears off.

[Amador]

Is there any way to get semi-permanent control over undead other than skeletons and zombies?

[Rhaegar14]

Be a Cleric. Rebuke Undead.

[Madara]

Undead Leadership and other stuff from the Book of Bad Latin