Have you heard of Facebook? Twitter? LinkedIn? MySpace? (I know, MySpace is kind of a dying breed). These are the major players in the social media genre. And soon to be Google+
It's not only a good idea, it's imperative to be on these sites, branch out to everyone you can, and provide updates or specials to your followers.
It's a great way to pick up new customers, and retain the ones you already have.
I can help you setup these accounts if you don't already have them, and I'll help you in keeping these networks updated on a regular basis.