You can resell your hotel reservation only if terms permits you to transfer the name on the booking (similar to plane tickets). Without a name transfer there is a risk that hotel won't able to check-in the person to prevent fraud. To avoid the surprise, it's good to confirm the terms with the hotel directly or just take the risk. See: Hotel early arrival for another guest
There are several services which offersthat offer secondary markets to resell non-refundable travel tickets (similar to Craigslist, eBay or StubHub) such as Hall St, Cancelon, ChangeYourFlight and other similar. See: New sites let you sell unused trips.