Brick Lane Market
The market began in the 18th century and now operates on Sunday's only (best from around 10.00am-2pm), in what was the centre of the Jewish area of East London but is now the centre of the Bangladeshi community.
While the market in Brick Lane itself is fairly legit, the streets around the area are full of pikeys selling obviously stolen or fake goods.
Also if your bicycle has been stolen, the market and surrounding streets are where it's going to end up - good if you want a replacement at a bargain price but irritating if you want it back. There are two stalls selling new bikes too.
There are a many stalls selling bike bits (new and "second-hand") which can be bargains - if you're prepared to haggle and know what you're looking for. Also one will do bike repairs on the spot.
Also many stalls selling tools and hardware items as well as a good selection of stalls selling bulk household goods such as soap, shampoo etc at knock-down prices and a few selling end of line clothes and fruit and veg.
There are also many Chinese selling pirate DVDs and fake brand name cigarettes.