You wouldn't want to use it as a hidden return, you'd get pretty poor airation that way. But give it a try putting the filter intake in it.
Just a thought, sounds like it's clear glass? So it wouldn't hide anything in it.
Hmmm, Now that I've thought about it a bit more, I think I HAVE seen a couple wet dry filters that might be set up using something like that. If you fill it up with filter media and have a power head pumping the water back out to the main tank it would just splash over all the media.
They'd be a pain in the ass to clean though and you'd have to be pretty careful of the amount of water in the tank, as it evaporates it would be the water level in the chamber that would drop until it runs dry.