I'm using NHibernate a lot more lately, and it's been working great. One of the downsides, though, is the fact that you need to build up the mapping files by hand. Well, no more. I stumbled upon the open source project, active-record-gen, on Google Code. One of the templates that it provides is one that will generate NHibernate mapping files for tables in an MSSQL database. I tried this on a couple of databases and it works rather well.

A few small suggestions:

• Implement a better pluralization/singularization strategy by using Inflector.NET.
• Work with more databases than just MSSQL.
• Allow for the connection string to be built up with more options. Right now, it requires SSPI integration, and attached databases don't work as well as they should. See here for more details.