Almost all areas with volunteer EMS (emergency medical services) and Fire Departments *ALWAYS* need people to volunteer and help out for everything from actually being on calls as an EMT or firefighter to helping maintain rigs to doing paperwork and fundraising. Many squads (or sometimes the state) will pay for all necessary training and equipment and most people find that there's a definite rush that comes from responding to calls.
EMS is a great entry into the medical profession and the skills/knowledge you gain are certainly *always* useful even after certifications lapse. The blood/etc actually aren't that bad when you're really on a call...I'd recommend getting your First Responder cert. and riding along with the local squad on a few calls if you're not sure if you can handle it. The squad I was on a few years ago also had all the extrication equipment (some towns leave it to the fire dept, others don't), so there were fun toys to play with during our monthly drills. Ever peel the top off a car? It's fun
Fire is, of course, somewhat more glamourous, potentially more dangerous, certainly requires you to be in great physical shape, but isn't concentrated solely on fighting blazing fires. I've only been involved with fire through my association with EMS, so all I know is that becoming a firefighter involves (in NJ) Fire School and possibly, First Responder and preferably EMT certifications.
Give it a shot...there's always a shortage even in volunteer/paid mixed squads
~Ladi