over the counter, non-accomodation sale items

Other than the usual drinks, bottled water, laundry, etc, has anyone found the sale of other stuff worthwhile? (we dont have a bar or restaurant). We sell padlocks and plug adaptors, which sell fairly well and solve an immediate problem for many guests, but I was wondering if there was anything out there that could also be sold succesfuly. Any snack foods you know of in high demand? We have begun experimenting with different stuff, and have started selling instant noodle bowls, lip balm and sheesha packs that can be purchased to smoke a hostel hookah.. too early to tell how these will work out.. but anyways, would be cool to hear experiences or suggestions..