Try Google AppEngine, Java and JDO. Install IBM Eclipse and the Google AppEngine plugin and deploy in two clicks. Move to VPS if you need more than what Google offers.
Do LISP/RDF research when code is up and running.
http://code.google.com/p/objectify-appengine/
The reason why Google chose JDO as the default interface to the AppEngine's datastore instead of JPA is because the datastore is not really a relational database and JDO is much better suited for non-relational backends.
However, there's a lot of stuff in JDO that you will never use in an AppEngine application.
Objectify is a thin wrapper around the low-level datastore API. It's a pleasure to work with and it will save you a lot of time.