Today I rented a hammer drill and a fitting for driving in ground rods
(they even had the right fitting even though they didn't know it and
didn't know what I was talking about...).

MAN, DOES THAT THING WORK NICE !!!

Took about two hours to drive 7 rods, after the first one (that I did
manually with a sledge hammer) took about 10 hours spread out over a week
(just for one).

Those of you who suggested a hammer drill really had it right, and saved
my butt... thanks. :-)

Somebody mentioned something about a battery-powered hammer drill. I
haven't been able to find anything like that... can someone tell me who
makes one?

Thanks again... :-)