I don't have a lot to add to the info already offered, just based on
what BeerBoy describes. I'd imagine a Lineman's Loop would fit the
bill in terms of the loop, but if he's still not satisfied with its
ease of untying, another alternative is a general purpose loop on the
bight (away from the rope ends) called the Span Loop:

http://www.geocities.com/roo_two/spanloop.html

BeerBoy, before you go out and pick up the Ashley Book of Knots (good
book, two thumbs up), you can browse my knot pages to see if they
help. It shouldn't take too long. You might start with this page of
quick definitions:

http://www.geocities.com/roo_two/glossary.html

Good luck,
roo