Yup, the one up near the lava spiral/lake in Ter Mur can have one spawned at any given time (at least on Chesapeake).
The spawn there isn't too bad but can get annoying since the mobs that spawn there are caster type (smoldering gargoyles, lava elementals, fire daemon).
I personally like the Fire Temple Ruins mini-champ spawn the best but that's because Chesapeake has a player house with a telepad right near there - it'd not be nearly as convenient otherwise I'd imagine. I'm interested in hearing of other spots that aren't in the Abyss, though.
fifteenth edit: UOGuide says they also spawn in desert areas of Ter Mur. That'd be mighty dangerous, probably; those snakes are a damn pain - especially the Kepetch ambushers.