There is also LINQ to LLBLGEN, which then can support many, many databases.
From LLBLGEN’s Feature Page
Support for SQL Server (MSDE, SQL Server
7/2000/2005/Express, SQL CE 2.0, 3.0,
3.5), SQL Server CE Desktop (New!), Oracle (Oracle 8i / 9i /10g),
PostgreSQL 7.4+/8.x, Firebird 1.x /
2.x, IBM DB2 UDB (7.x/8.x/9.x), MySQL (4.x, 5.x), Sybase Adaptive Server
Enterprise (ASE) (New!), Sybase SQL
iAnywhere (ASA) (New!) and MS Access
2000/XP/2003/2007