Prevalence is by far the fastest, simplest and most transparent business object persistence, ACID transaction, fault-tolerance, replication and load-balancing architecture we know.

I find this concept amazingly cool. I recently (almost) got sold on the idea that databases are not worth the hassle and you are just as well off with using files - the same way Paul Graham describes what he did with ViaWeb. But this is even better - and for a big majority of systems, it should be the optimal solution.