Just finished .NET Micro ORMs, by Steve Michelotti, on PluralSight.
This course covers a few Micro ORMs for .NET – including Dapper, OrmLite, Massive, PetaPoco and Simple.Data.
It was very interesting to see how easy they are to use, and how fast they are, compared to Entity Framework.
From my very limited experience, the best for me seems to be OrmLite – which is not surprisingly a paid product (although it has a free version for up to 10 tables in a project, which can work in some situations).
All the others seem very interesting, though.