OpenTSDB is an awesome Time Series Data Base that can ingest and store an insane number of metrics. Written by Benoit Sigoure to run on top of HBase, it's easily scalable to storing millions of data points per second with built in Hadoop redundancy.
I've been working with Benoit to coordinate the official 2.0 release and we're making excellent progress. Click through for documentation on what's been accomplished so far and what's left to do. We had a great time designing new features and chatting with users at HBaseCon 2013. I'll be posting some tutorials for OpenTSDB as well as the Async and Asyncbase libraries in the future. In the mean time, join the OpenTSDB user group for discussions and updates.