Earplugs

Earplugs can be a sanity-saver for light sleepers in crowded hostels. The soft, yellow, foamy type work well (try at a pharmacy), and you can sometimes get these free on your flight over the Atlantic. Try out your earplugs before leaving, because they can take some getting used to, and bring several pairs.

The ever-popular universal drain plug

Every year hundreds of retired tennis and racket balls are reincarnated as these devices, used to plug stopper-less sinks for laundry and other chores. Just cut a tennis ball in half, and trim to the size desired. Use with smooth side down.