I have Dwarf Frogs, Guppies and a Bamboo Shrimp together quite successfully. The shrimp just molted and the frogs and guppies never once bothered him, in fact, the guppies completely ignore him at all times and at most, the frogs just kind of climb over him like an obstacle. The shrimp is beautiful and udderly entertaining, do get one (or more), just make sure they have a proper place to hide and that there is enough for them to filter out of the water, or you'll have to add special food. The frogs and guppies are fine together as well, however, with the caution that the frogs will eat the babies - and if allowed to do so, they will more or less eat themselves to death. So if you don't want the babies to be eaten or the frogs to overeat, you'll need to have a plan for that (like seperate breeding tanks (or the floating kind) for the pregnant guppies). The frogs are a blast though, and if you can get it worked out, you'll definitely want to get some. They are very social and interactive. The males do wrestle, but they don't harm each other and it is pretty cute. They also sing at night. The frogs are trainable. I handfeed mine blackworms (one at a time to prevent the worms from escaping into the substrate) and it didn't take the frogs long to learn that hand means food, and now they'll swim right into my hand and try to nibble at me. They add such clownery and personality to a tank.
I would absolutely not do crabs with the frogs, though, as they are so soft and tend to hang around the bottom of the tank and may get injured when playing leapfrog with a crab. Small shrimp get eaten by frogs (who will eat anything that even remotely fits in their mouth) but Bamboo shrimp are quite large. Also, for frogs, stay away from sharp edged substrate (and I'm not a fan of dyed substrates either for that matter) and don't put anything in the tank that could trap or pin down your frogs as they need to be able to breathe at the surface (something else which is fun to watch them do).
