FOSSGIS e.V. is runnning a development server sponsored by Strato AG for experimental services for the OpenStreetMap community. Unfortunately not a hell of a lot happened since the servers has been announced
Being one of the admins, I finally started to get the projects running. Unfortunately all of them desire a lot of computing power and as far as databases are concerned we seem to need PostgreSQL as well as MySQL. The former for its geospatial capabilites the latter for speed (if just a limited set of features is required).
If you are looking for data which still proves a challenge for decent computing power just go for processing OpenStreetMap data in various ways
I don’t think that we can handle all the projects on one or two machines in the long run, but on the other hand we need to figure out data formats which are suitable for a many projects as possible.