LINQ
I have mixed feelings about LINQ. I don't want it interfering with my database, and running queries against it so I think I'll be sticking to stored procedures for this type of access. However, there are also cases where I think it is very useful.
Here's a blog post from my friend Christiaan Baes on an useful implementation of LINQ to order directories by creation date:
http://blog.baesonline.com/2008/01/17/OrderingDirectoriesByCreationDateUsingLinq.aspx
Edit: As Fabrice pointed out in one of the comments below, it's really DLINQ that I'm saying I'll be avoiding, and not other LINQ methods.