What to do with a 20 gallon tall?

[Dawnrider]

I have just finished transferring Drake over to his perment homemade 50 gallon tank, but know I have a empty 20 gallon tall. I have a feeding tank but this tank might serve as a better one (the old feeding tank is a 15 gallon tall wire mess cage with under tank heater making it quite warm). Any ideas what I should do with the 15 or 20 tall? Any ideas would helpful. Maybe in the future (say March) I might be getting a new lizard, it would have to be an arid to moderate humidity loving lizard, so I am looking at the following: Another Mali uromastyx, another beardie, a leopard gecko, or a sudan plated lizard. I intend to buy a cage for any of the species then so this cage (either the 20 or the 15) wouldn't be for them.

 

[Dawnrider]

Okay here are the photos of the tanks i was talking about. just click on the image to get abetter view.

This is the 15gal, it has a undertank heater, no lamps on it right know but I got plenty of extra heat lamps and supplies

This is the 20gal. I stole the UVB source for it and put it in Drake's new tank but I have an extra MVB bulb (100watt) I could use in this tank. This tank also has a undertank heater as well as a hygrometer. I have extra digital thermometers as well (I only use digitals)