I hadn't heard of Airbnb until my husband found it via a web search for accommodation for our trip to Copenhagen. Copenhagen is infamous for its expensive hotel accommodation, especially if you need to travel with children. Airbnb offers you the chance to stay in a real home in many places across the world. For us it meant that we could stay in an apartment in the heart of our old neighbourhood with a bedroom for us and one for Noah plus a huge kitchen and beautiful living space for less than the price of a night in one room in a hotel. It made our trip very relaxing and enjoyable especially as there were toys for my son to play with.
I would certainly use Airbnb again. The admin side of it takes a bit of time as you need to register and, as you are asking to stay in someone's home, you need to make sure there is a bit of honest information about you on the members' section of the website so prospective renters can get a feel of you, but it is worth it. You can also list your own place for rental.
When friends are planning to visit us in Copenhagen, I would certainly recommend the place we stayed in.
This does sound a bit like a sponsored post (which it isn't) but I was so pleased with the opportunities that this website has opened to us for future city breaks and also that so few people I have mentioned it to have heard of it, I wanted to share it here.