The spell lesser animate dead from Ultimate Magic can create a single Small or Medium skeleton or zombie; it's 2nd level for clerics and 3rd level for wizards.
The spell animate skeleton from Rite Publishing's 1001 Spells can create a single Small or Medium skeleton only; it's 1st level for both clerics and wizards.
The main difference with this spell is that the skeleton it creates doesn't count towards your HD limit for controlled undead, but you can only control a single skeleton made by this spell; casting it again frees the previous skeleton from your control.
Now, what I want to do here is have a 3rd-level necromancer who can animate a humanoid skeleton. I personally think lesser animate dead could be kicked down a level, allowing the necromancer to cast it. But would it be better to do that or use animate skeleton instead? I think the spells are too similar to use both in the same game.