With the current move to cloud computing, the need to scale applications presents itself as a challenge for storing data. If you are using a traditional relational database you may find yourself working on a complex policy for distributing your database load across multiple database instances. This solution will often present a lot of problems and probably won’t be great at elastically scaling.
As an alternative you could consider a cloud-based NoSQL database. Over the past few weeks I have been analysing a few such offerings, each of which promises to scale as your application grows, without requiring you to think about how you might distribute the data and load.