Cloud + OSGi + GWT + ECF Rest + Twitter API = Modular web services
Using several technologies, I've recently created a Twitter user status service...i.e. a web service that retrieves the latest user status for a given user.
The use of OSGi modularity makes this not only possible, but lightweight...as this server/service consists only of the bundles necessary to actually provide this service...and each of those used are small.