[slig]

If you'd rather use a native client with loads of features, including blocking people and keywords, give YoruFukurou a try https://sites.google.com/site/yorufukurou/home-en

[notjoeflynn]

Hibari (http://hibariapp.com/) is another native OS X client with muting (and, in my opinion, a nicer interface than YoruFukurou.)