My current list:

Another ball...or two or so...
Cresties or Gargoyles, possibly both
Standings Day Gecko (I really like some of the other day gecko species, but I think one you can hold would be easiest in case of escapees)
Green Tree Pythons, although I want to start out with an ATB, since they're supposed to be easier to start out with

In the case of the geckos, I'd like to start out and then try breeding. I may also try to breed balls in the future. I also plan on starting out with the cresties or gargoyles before I make a move on the day geckos, becuase I think they'd be easier.

There are some other snake species I'm interested in, but they can wait for quite a while. Also, someday I'd like to hold a giant gecko...i dunno if i want to drop the 400 or so to own one though.