Q & A plugin notifications

In the Q & A plugin you have the option to be notified when someone replies to to a question. You do this by opting in for this while viewing individual questions. My question is how to extend this feature. For example, can I let my users create a filter of keywords and have the site email them every time a question that has a tag that matches one of their keywords gets asked? Essentially I want to create a system where it will be easy for people to know when questions they are interested in are asked. Thanks!