This extension will notify you in your browser when you've been cited, a topic on your watchlist gets a reply, or you get a PM. You can add it to Chrome by downloading the file, and then drag & dropping it to your tools->extensions page. More info here.
This application will notify you when you've been cited or a topic in your watchlist gets a reply. To install it you need to enable untrusted sources in your devices' settings like so:
Use these at your own risk!