[EdinSumar]

I know that on some servers they do it alignment based, for example:

A Good Aligned Wizard would always summon good-aligned extraplanars, such as Lantern Archons and Divine Avengers, strength according to level.

An Evil Aligned Wizard would likewise summon evil-aligned extraplanars, neutral would summon according to Law/Chaos axis (Formians/Slaads respectively).

And then more specific stuff for some of the deities, such as Fire Elementals for Kossuth and such.