My current development endeavors have brought me to the world of Pervasive, a Btrieve-based relational database back end. Pervasive ships with some generic ODBC drivers, but I just stumbled across a Pervasive ADO.Net Provider this morning:
http://www.pervasive.com/developerzone/platforms/net.asp
I'm sure that most of the developers out there who read my blog (all 1.5 of them) are drooling over this right now. Most developers have never heard of Pervasive, but maybe this will come in handy for someone years down the road.