Given how young node.js is it has a lot of modules including:

Redis http://github.com/fictorial/redis-node-client

memcache: http://github.com/elbart/node-memcache

MySQL support using DBSlayer

And it's fairly easy to implement other stuff using node.js's TCP module. This said, it could definitely use more modules, but it's a young project and I am sure they will come.