MySQL + WCF Data Service Error "Failed to find or load the registered .Net Framework Data Provider"

This little thing took me about an hour of angry googling (that's my daily job lately) to fix. So, you want to use WCF Data Services to expose data in your MySQL database. You created a project, added ADO.NET Entity thingy, added WCF Data Service, and this last guy does not work throwing Failed to find or load the registered .Net Framework Data Provider at you.

The only thing you are missing is a reference to MySql.Data.Entity (if only it could add itself automatically like tens of others). Go and add it: References -> Add Reference -> Extensions -> Check MySql.Data.Entity. There are a lot of versions available. My installation required version 6.6.5.0. If you add wrong version, the your server will throw an error that would tell you which version it is looking for.