My DM created a small table just for the battlemat to be placed on the gamer table. He cut a piece of plywood to be the exact size of the battle mat. Then he cut a 2 inch by 2 inch stick of wood into four table legs. We determined how high it should be by taking our HERO Games book (the thickest book we own) and opened the cover so that it was perpendicular to the book. We decided that the table should be high enough so that we could open this book while it was partially underneath the table. We put each leg so that it was halfway between the center of the table and a corner of the table.
Then he put hinges on each leg so that they could be folded into the table for storage.
He put latches on the middle of the legs so that they would stay put when they were folded into the tabletop and latches where they meet the tabletop so they would stay put when they were extended out.
He put a handle underneath the table so that we could easily carry it around if we wanted to transport it.
He put felt on the bottom of the table legs so that it wouldn't mar the table that it was resting on.
This has worked wonderfully. The battlemat is always clear of books and papers, while remaining viewable by us while we are seated, and there's plenty of room for us on the main table for our books, papers, dice, food, and beverages. We put bowls of chips and other snacks underneath the small table so that anyone can reach it. We have been using it for several years and I can't think of how it could be better.