Where can I get my fire extinguishers recharged?

I would guess you are talking about the 'no longer manufactured' Halon systems.
Get out your yellow pages and look under fire protection or fire extinguishers. Most of the places still service Halon systems, and they can be recertified/recharged (Halon is being recycled just llke Freon 12) by a licensed shop such as these.
Jim

Since Halon is not a coast guard approved fire extinguisher for an open environment, can an extinguisher previously charged with Halon be easily converted to an approved retardant?

I have nice chrome units, would be a shame to toss em.

Jim, I don't think it is halon - I want to say it is actually a (bc) extinguisher. I will check out the yellow pages. Don't want to throw it away because is it one of those fancy chrome ones from Eddie Marine.

Keep the unit and buy two new ones. It never hurts to have more than the recommended number on board. Cheap insurance.

Your yellow pages will have several "mobile" fire extinguisher recertification guys in it. We have some guy come by every year and recert ours.

Halon 1301 is most CERTAINLY USCG approved, but is no longer commercially available in virgin state.

Take my word for it that there are recert guys out there who "will" recert your Halon unit with the correct Halon gas. The "green" replacement for Halon is corrosive to metals...