Check out this blog post by Ian at A Teacher's Thoughts. He give s description and links to 3 math sites. These sites are geared more for elementary students, but they're worth checking out even if you teach Middle School.
I believe that math should be much more about learning concepts and problem solving skills than on Drill and Kill. However, students do need to master some basic skills. These sites could provide some good options for students who need extra practice with basic skills.
A Teacher's Thoughts: Make Math Fun: 3 Sites You Should Try: "Teaching math can often lean towards drill and kill. I know this because our current program, Saxon Math, spirals the teaching of math facts..."