HaterAide is a simple ORM created in C# to work with your .Net business objects. At present it's rather basic and deals with SQL Server, however it is extendable so you can write your own cache and/or database provider without too much of an issue. I even took the time to write a 7 part series showing initially what was done, the choices that I made, and why I went the route that I did.
Since then much of the code was rewritten to allow for better readability, performance, as well as a number of functions that were not added initially. To download the latest code and to be kept up to date, please visit the page on CodePlex here.