Here's a brand new one: https://github.com/dradovic/MigSharp
It has support for SQL Server 2005/2008/CE 4, Oracle, and Teradata. It also includes a nice validation framework that checks your migrations for potential cross-db issues and gives you hints to how to resolve them.
On top of that, it has a couple of more interesting features: multi-module support, deterministic SQL generation, etc. Read on here: https://github.com/dradovic/MigSharp/wiki/Feature-Overview