LLBLGen
LLBLGen is a simple open source tool for Object-relational mapping in .NET. Unlike many O/R mappers, LLBLGen works entirely through stored procedures; a Transact-SQL script is generated that defines a set of stored procedures when run, and the corresponding C# layer only accesses the database through the generated procedures.
LLBLGen is separate from LLBLGen Pro, which is a more powerful commercial offering from the same company. Since The Release of LLBLGen Pro, LLBLGen is no longer in active development, the latest version v1.21.2003.712, being released on July 12, 2003.