Imalizard - There are plenty of smaller lizard species that could be kept in a 3ft tank...
Dragons - Central Netteds would do fine, any of the smaller dragons (Crevice, Mountain etc) would be fine...
Monitors - Brevis would manage, and if it is 2ft deep you could probably even manage some Gillens...
Skinks - A HUGE number - check out Danny Browns website for some of the smaller skink species...