I've done a couple things, depends on how nice you want it to look and the location of the hole. For a quick, down and dirty fix I've smoothed a spot of quick dry epoxy over a smaller hole. For a nicer looking fix I've taken canvas, cut *two* of the size of the patch that I want, coat the backs with spray on adhesive, and put a patch on each side of the hole. After the patches have seated a bit I shot them with scotch guard. The durability of these depends on how much bending/flexing that part of the top is subject to.
Good luck no matter what you end up doing.