This one looks like a great .NET lightweight ORM:
PetaPocoA tiny ORM-ish thing for your POCOsPetaPocoMainDocumentationLicensePetaPoco is a tiny, fast, single-file micro-ORM for .NET and Mono.Like Massive it’s a single file that you easily add to any projectUnlike Massive it works with strongly typed POCO’sLike Massive, it now also supports dynamic Expandos too – read moreLike ActiveRecord, it supports a close relationship between object and database tableLike SubSonic, it supports generation of poco classes with T4 templatesLike Dapper, it’s fast because it uses dynamic method generation (MSIL) to assign column values to properties
Source: PetaPoco – Topten Software