There's a brand new addition to the 'rent it out for cash' family.
If you don't use your car all the time, you can hire it out by the hour or day via clever new site www.whipcar.com. And there is no need to worry about the insurance as, when someone else uses your car, this company automatically insures them and it supersedes your policy.
Renting out to boost your income doesn't stop here, though. With websites like parkatmyhouse.com, you can rent out your parking space or, if you take somebody in under the 'rent a room' scheme, you won't have to pay tax on the first £4,250 made each year (though you can't then claim expenses). Plus, as a landlord, you can ask for a deposit and a month's rent in advance, which means ready cash comes in quickly.
These are just the tip of the iceberg though, for a full list see www.moneysavingexpert.com/boostincome