Very simple pet to keep. In fact a lot of froggers have tanks setup where they don't even need to touch or feed the frogs for months at a time....I'd say they are the easiest herp to keep lol.
Basically if you keep their environment well, their environment will keep them well.
The general rule is one frog per 5 gallons, however some are dominant so it is better to start off with 2 or 3, get to know them, and add one at a time from there to see the dynamics in the relationships.
All you really have to do is set up a vivarium with the right soil and plants, a misting and drainage system is good but not required, toss some tropical woodlice and springtails in, let it sit and grow for about 2 months, then add your frogs!
The only pain can sometimes be making fruit flies. However, the new SuperFly by Repashy is a Godsend. Simple, nutritious, no smell, affordable, and makes a ton of flies.
I would recommend Dendrobates tinctorius, D. aurauts, D. leucomela, D. azureus or Phyllobates terribilis as great, large, visually stunning, active display pets.
They are my favorite pet to keep aside from chams.
www.dendroboard.com
www.canadart.org
www.joshsfrogs.com
www.dartfrogz.com
www.frogforum.net