I'm working on a database-driven web service with clients in the US and Australia. We're currently hosted in the US, however our Australian clients are experiencing lag. The lag is primarily due to the fact that the pages launch AJAX queries which require some db work to be done on our database in the US and these take a while to perform a round trip.

Ideally, we're looking for some kind of distributed database system which replicates our main US database in Australia (and possibly other locations if we choose to expand later on).

Does anyone have any suggestions for services which offer something like this? Something like a CDN (CacheFly etc), which is web-based, simple to set up etc but for databases instead of static files.

Ideally it would be completely transparent to the application and abstract away all the distributed database management, syncs etc.