Here is a great overview of the current landscape of freely available distributed hashtables (DHTs), by one of the founders of Last.fm.
Anti-RDBMS: A list of distributed key-value stores
I've looked at several of these systems in the past, but was delighted to see coverage of even more recent developments like Project Voldemort -- apparently used by LinkedIn.
I still have a need for some system along these lines. My "excerpt server" BDBs are 120 GB and growing forever, with periodic bit-rot errors cropping up, necessitating reconciliation between replicas. I'd love to have a solution that I can throw more data+traffic at that just works.
