We’ve had Sifter’s repo hooked up to Code Climate for a couple months now and I’m really loving it. Garrett and I have both found it fun to kill duplication or refactor away complex code. A decent test suite enables this, but Code Climate is very much the compass that points you right to the trouble spots. The Code Climate blog is a great read too, consistently featuring thought-provoking ideas on how to think about making better code.
I love tools like flog and flay for quick smell detection. If you are like me and too lazy to configure CI and code metrics, Code Climate’s easy setup and awesome trending are well worth a look.