what nosql databases are available for azure

If you're looking for alternatives to SQL Azure, look at Windows Azure Table Storage APIs and this wiki page Data Storage Offerings on the Windows Azure Platform. I've also see others run MongoDB within a worker role, though a word of caution, if you're looking for easy management and out of the box scalability without having to set it up on your own, Windows Azure Table Storage is the way to go.

I've gotten MongoDB to work in an Azure role, both as a standalone and a replica set, although replica sets are rather tricky (at least in the proof-of-concept I built) and I haven't worked out details around graceful shutdown and a few other things. I demo'd this at MongoSV last year (video here).

10gen (creators of MongoDB) have now formalized this, with a MongoDB configuration which runs as a standalone server in an Azure role. With this configuration, you could even scale to multiple instances, which would provide a "warm standby" server in case the primary server went away for any reason. You can read the documentation and grab the latest code (currently alpha) from here.

You should be able to run other NoSQL databases as well, provided you can either xcopy-deploy or run an unattended install.