Tasos Yalanopoulos has a great post about a replacement for the intrinsic SoundEx function, called SimMetrics, implemented as a CLR library that can be loaded into SQL Server. The library has a number of methods for determining similarity metrics.
Tasos’ post is Beyond SoundEx – Functions for Fuzzy Searching in MS SQL Server, and contains a tutorial of how to load the library into SQL Server, and how to use it in queries.