Free Cloud Databases

If you're looking for a Free database on Cloud 

consider these options:

XEROUND
Up to 10MB at no charge. Best suited for small web apps and development or staging purposes.http://xeround.com/mysql-cloud-db-overview/pricing/

Amazon SimpleDB
It could be useful for very basic use cases
http://aws.amazon.com/simpledb/

Google AppEngine Data Store
https://developers.google.com/appengine/docs/quotas?hl=ru#Datastore

Cleardb
Price: FREE. DB Size: up to 5MB. Connections: 10. I/O Performance: Low. Daily backups.
Great for getting started and developing your apps.
Database.com

CouchDB
NoSQL, it's FREE
Read this article: Why Large Hadron Collider Scientists are Using CouchDB.

Microsoft SQL Azure Database
FREE???
http://www.windowsazure.com/en-us/