The following items are not essential for your travels but will make your life a hell of a lot easier, especially if you’re on the road for a longer period of time than the average holidaymaker.
String (clothesline) + clips
In Phnom Penh, Cambodia I saw a Japanese girl in my room stretching a string across her bunk bed to hang up the clothes she just hand washed to dry and thought that that’s a brilliant idea for long term travel. It’s probably even more useful for drying your swim wear when you’re staying in a seaside town. In addition you can use the string to put up a makeshift curtain for your bunk for a bit more privacy.
The versatility of a sarong is amazing: you can use it as a clothing item (dress, skirt, bag whatever), blanket, emergency towel, curtain for your bunk (in combination with a string/line) etc. There’s no limit to your creativity and you can probably come up with even more ways to use a sarong. It doesn’t take up much space in your backpack, so why not bring it on your next trip?
If you’re staying in a dorm a reading light can come in handy, as a lot of hostel rooms don’t have them next to every bunk. Obviously, I don’t really have to describe the benefits of a reading light as they are self explanatory.
A problem in many hostel rooms is the lack of power outlets for everyone to charge their electronics at the same time (at night). So you don’t have to leave the room with an uncharged phone, you can charge your portable power bank the day before in the hostel while you’re out exploring and use it when needed, which gives you greater independence when your dorm mates are blocking the outlets. Obviously power banks are also great for long journeys.
Don’t forget to check out the 6 Hostel Essentials!