Newts are fairly hearty - i had one for about 5 years with minimum maintenance. i had a firebelly so I can speak to their calm temperament. what about crabs? i know they sell them at my lfs.
you can buy shrimp from members here at the forums too just a fyi
I got my red cherry shrimp from a member and I love them. Got them in 2 days and no DOA's
I ended up getting 2 fire belly toads. They're happy and croaking at night & trying to mate... well the male is anyway, the female doesn't seem too interested.