Ruby clients for Riak. (See also: Ripple -- http://github.com/seancribbs/ripple)

Dataflow / MapReduce coordination framework.

tools for benchmarking Cassandra

A Riak-based Wiki-like application.

A NIF wrapper around a basic bloom filter.

a branch of Mochi Media's excellent HTTP library -- their canonical source can be found at http://code.google.com/p/mochiweb/