I've been using a product called LightSpeed, it works very well and seamlessly integrates into Visual Studio 2010 & 2008. I have been using it with Sqlite, however it supports numerous rdbms. It also has a very nice feature that allows you to create POCO objects that can be used with WCF, great time saver! At first I was using the free Express Edition but soon upgraded.
LightSpeed is the best high performance .NET domain modeling and O/R mapping framework available. First class LINQ support, Visual Studio 2008 & 2010 designer integration and our famous high performance core framework means you can create rich domain-driven models more quickly and easily than ever before.
