Relevant ability:
Deathless Master's Touch: A living foe of up to one size category larger than a pale master hit by the pale master's touch attack must succeed on a Fortitude save or die. A slain creature automatically animates 1 round later as a zombie and is under the pale master's control as if he had animated it. Undead created using this power do not count against a pale master's HD total for controlling undead.
3 uses per day, with a respectable save (caps at 20+Cha without outside modification).
This means that anything that can be zombified can be assumed to be one of your minions as long as its fortitude save is lower than your charisma modifier.
What do you do with NI minor minions? You can fit 40,000 Hairy Spiders in a Type 4 bag of holding, but only 40 of them can attack a target at once. They could get surprisingly deadly though once they get the zombification bonuses (it says "as if he had animated it", so I assume necromancy buffs work here).
On the other end of the spectrum, what's the beefiest thing you can grab with this? Let's say under +12 fortitude (30 Cha, 2 from ability Focus). Unfortunately, most things that make good zombies have good fortitude saves...
Going by the bad save formula (HD/3, which is Humanoids, Monstrous Humanoids, Fey, and Abberations), there's probably some 30HD monsters out there that are solid by sheer virtue of being 30HD, even with zombified bodies...