Given that it isn't strictly a present then I'd be inclined to bring something you may all enjoy on the occasion, which does tend to suggest food or drink.
Unless you are suggesting you feel so guilty you wish to renege on the no-present agreement.
No flowers, no chocolate... hmmm... Well maybe a large container of sweets, perhaps a video or two that all would like to spend a couple of hours watching. Aside from that as others have suggested, booze is the obvious choice. Unless you want to do something outlandish like bring a ham :-)