I found Camden Lock Market to be more hip and stylish than the other street markets in London. The shops around the outskirts sell goth and techno clothes, high-priced fashion shoes, and even juggling equipment. You won't find the antiques of Portobello Road in this market, but it was my personal favorite simply for the variety and personality available. The entire area is a conglomeration of vendors selling their wares in a variety of formats.
Two buildings house stalls of artisans, booksellers, and more, but that is just the beginning. Long walkways stretch between the areas and are lined with vintage clothing, music shops, world goods, and trendy boutiques. Each tent, pavilion, or stall has a specialty, from military apparel to wooden furniture to pop-culture iconography. One shop deep within the market blasts pumping techno music and offers the wildest fashions for clubbing - think spikes, huge foam, fluorescent colors, and skimpy syles, worth a trip simply to broaden your horizons.
The main food area offers pavilion-style seating and any type of food you could desire. There is also a corridor of mainly Asian cuisines whose sellers will accost all passerbys. However, if you arrive at the right time, around 3 or 4 in the afternoon, they are trying to get rid of their day's food and will offer you drastic reductions. In the colder times of year, mulled wine, a British classic, is always a good choice. Or grab a fresh crepe (plain nutella are the cheapest, but classic and absolutely delicious) served folded into a cup to tear off bites with your fingers as you browse. Exploring this market takes some time, but if you have an afternoon to wander the stalls, it is a beautiful location and a place to find more than the tourist trap shopping.