Depends, if you are making a big purchase you can still find the Companies selling the items offering interest free loans ie: cars, suites of furniture.
If you are looking short term, a 0% introductory rate is available on credit cards and if you 'play your cards' correctly you can transfer from one to another at the end of the free term. However scrutinise all the rules of any cards very closely.
If very short term, there are Bank accounts around that give interest free overdrafts as part of their package.