As was already stated, the first responder is a level of training designed primarily for LEOs, fire fighters and industrial sites. Its basically a glorified first aid course. You will learn the fundimentals of patient assessment, oxygen administration (actually that's an optional topic), common medical emergencies, treating basic trauma, etc. It's like EMT-lite, the same basic topics, but not as much detail. I don't think people looked at me "wierd" at the time, mainly because the majority of my fellows were also FRs.
As for what you can do with it...that really depends on your area. I got my first responder simply to have some medical training because I hiked/climbed/etc in the backcountry a lot. After getting it though, I started volunteering for a fire department (which eventually led to me becoming an EMT and then a paramedic). I teach FR classess occasionally, and the majority of my students are from small volunteer FDs and search and rescue groups. EMT is becoming the standard level of training for most urban fire departments these days, but really...the idea of the EMT class is really to train someone to work on the ambulance, FR is more aimed at people who will serve as an intermediate between a lay person and the ambulance crew.
I absolutely don't regret taking my first responder class...if I hadn't taken it, I probably would not be going to medical school next fall. Before my class I was interested in computers and engineering...I had never even taken a biology class!! It changed my life...but that's probably not true for everyone!
Nate.