I don't have the technical skills to do this, but I would suggest something like this:

1. Find sources where you would find things of interest to you, if they were happening now.
2. Create a tool (or script or something) to scrape their "events" page at regular intervals and then sorts that data, searching for keywords
3. Have it then notify you in some context when something you like is mentioned.

This isn't foolproof (for example, it might say "Band X is the next Beatles!" if you've chosen Beatles ... but then you might find something you like). Pages like meetup, local ticketing outlets, facebook community pages, etc. are a good source. If you google about you might be able to find instructions for doing something like this.

There's also a website called www.ifttt.com which is essentially an "if this, then that" formula for the internet, but it only works for certain websites, and you need an account. It may serve your purposes, though - you could link it to twitter and get emails if given accounts mentioned the word "tour", "concert", "show" or any other relevant word. That's the closest tool that already exists that I can think of.