Caecilians:
Typhlonectes natans (kept several in the past, no longer available)
Ichthyophis kohtaoensis (very cool)

Frogs and Toads:
Xenopus borealis
Pipa pipa (kept some in the past, would like more)

Salamanders/Newts:
Axolotls
Iberian ribbed newt
Dicamptodon ensatus