My personal favorite, and also the one I am using during my current project, is LightSpeed by Mindscape.
It features a great feature set, very good support, and is a lot more "polished" feeling to make use of than the majority of the other available choices I have attempted, including ADO.Internet EF and NHibernate/Fluent NHibernate.
A fascinating (though somewhat biased, IMHO) website which compares different ORMs is http://ormbattle.net/.
Probably the most prevalent appears to become NHibernate, I imagine because of it's maturity cheap it is dependant on Hibernate for Java. I am focusing on learning it now, so that's all i'm able to say about this.
Others within the ORM space are SubSonic and
MEF (Entity Framework). I barely know anything about the subject, apart from being NH options.
.NETTiers is yet another interesting option
A Ruby script I made a while ago which was producing everything. Obtaining the schema in the database, saving it as being XML, looping regarding this and spitting out anything you become a template matching a table. Aside from the ORM, there is lots of UI components, web services, etc. which i added later. I truly loved it.
NHibernate has everything you will need (well almost) which is open-source