We have a couple of these: http://www.wiggle.co.uk/saris-bike-bunk-cycle-rack/
Work well in rented places as they just lean against the wall, there’s padding to ensure it won’t mark the wall. All the weight is taken by the T-piece on the ground. Preferable to the “stripper pole” types – a couple of friends have had theirs fall over, and it’s easy to damage the celing with them too. To be honest, they’re a bit pricey for what they are, but would be quite easy to make a DIY copy. Think I’ve seen a similar one made out of IKEA wardrobe bits somewhere.
They’re quite good for hanging washing on too 😀