There are a whole lot of dwarf geckos, many from the genus Sphaerodactylus that do well in small enclosures. You could also consider a banded gecko from the genus Coleonyx, which has care similar to a leopard gecko but is much smaller.
Here's a website that describes many dwarf geckos: http://www.dwarfgeckos.com
Here are some articles from Gecko Time about Coleonyx and Sphaerodactylus:
Introducing our new monthly Gecko Time feature --Three to Get Ready. Every month, a different herp species will be profiled by three experienced keepers. While a detailed caresheet is always useful, individuals' personal experiences and their delight in working with a particular species can do...
It was touch and go as to whether I would find three experts to share their experiences with keeping the somewhat rare genus of tiny geckos, Sphaerodactylus. Imagine my surprise when I ended up with no less than five contributions from the United States, Canada and Europe. More