Hmm.. I know many dart frog keepers keep phelsuma in with their darties, however I would question a gecko such as a Crested in the way that they lick things a lot more in their surroundings. The secretions of the frog may be possibly dangerous to the gecko.
I know a lot of people put millipedes in crested geckos enclosures but honestly that is all I've really seen.
Dart frogs make their poison using some component of their wild diet, so in captivity they don't make the poison at all. Millipedes do secrete a toxic substance, though. Intensity varies with the species. I'd love a dart frog / day gecko setup!
Not sure if this will help. I had a friend that kept a large whites tree frog in with her crestie and they co existed without a hitch. They were together for years adn still are i think.
oooh thanx all, I may just get a dart frog...I find that even though I know it's poorly looked upon, I do have my crestie in with my chams in a medium sized reptarium, he stays away from them, and visa versa, the chams don't seem to mind him in there either. No one turns dark when he goes by.......
I have to add this....my male veiled is on my head at this very moment.......he seems comfy in my hair!!!