Bosun
Time Series Alerting Framework
... monitoring agent (Currently works only with OpenTSDB) scollector for Windows, Linux, and Mac. Use Bosun's flexible expression language to evaluate time series in an exacting way. Scollector auto-detects new services and starts sending metrics immediately; properly designed alerts will apply to these new services which reduce maintenance. Create notifications using Bosun's template language: include graphs, tables, and contextual information.