This link was posted yesterday on the Gesneriphiles list and I found it fascinating. It is a checklist of gesneriad species that can be searched by genus, or by location. I was using this to see what gesneriads were known to be native to various countries around the world. I haven't learned so much about gesneriads in a long time. I found I was misinformed about the native location of many gesneriads. Looking at countries in asia I saw vast numbers of species that are not it cultivation. There is so much out there for us to wait for! Places like Papua New Guinea are just loaded with uncultivated gesneriads--many of them lipsticks. This is a great link, I think.
Here is a link that might be useful: gesneriad checklist (Smithsonian Botany Dept.)