In my blog stats, I can see how people find my blog. Usually, I think that they'll find what they are looking for. But I had a Google search a few days ago about co-habitating hermit crabs and bearded dragons and this is not a good idea for so many reasons. Don't even think about trying this. Bearded dragons are desert animals, while land hermit crabs need a humidity of at least 70, better 80% - way too high for dragons. The crabs can't breathe when the humidity is too low (not to mention that they would dry out eventually). And you can't find a compromise between their needs, that would mean that one or both of them would suffer.
Good info on bearded dragons can be found here
and good info on land hermit crabs here
Co-housing animals is not something you do to save space or because the tanks looks a bit empty (while all your crabs are molting for example). It usually not a good idea even with species that share the same habitat since in most cases they have their own microhabitat and have different needs that can't be met in one tank. To co-habitate two species with the same needs, you need a bigger tank that you would need for housing each species alone so that they can avoid each other and so that you can create the perfect conditions for each species. You should also be experienced with keeping both species alone for a few years to make sure you recognize signs of problems (stress ect.) right away. In most cases, it's better not to try.