No longer active because of my medications following a heart attack. I was, however, a regular platelet donor before that happened.
It's very worthwhile to donate, especially if you find you're in one of the more unusual categories, eg I found out that I was CMV negative.
I don't know if it's still the case, but donors could give platelets 15 times a year with a minimum of 14 days between donations. It does take a bit longer than whole blood donation (which is also very worthwhile) but there's a lot less hanging around as you are expected for a timed appointment.