Wired on Friday: There are a plenty of blogs out there on the internet, covering obscure, niche topics. Occasionally, one of those narrow obsessions taps a mass market fascination.

Take Jason Cosper's website, http://preshrunk.info/, a blog devoted to new T-shirt designs. Every day or so, Cosper puts a link to a shirt with a catchy logo or an amusingly indecent slogan.

Is there really an audience for T-shirt reviews? Anybody who has watched the struggle of the internet economy could answer that. There's a huge market for new T-shirt designs on the internet; it would be only a slight exaggeration to say there's a larger market for new designs than there is a market for T-shirts themselves.

Just browse through a site like CafePress (http://www.cafe press.com/), which has provided a service for creating personalised clothing since 1999. You'll see that it's as easy to set up a store selling a T-shirt with your own design as it is to buy one.

The result is more than eight million designs, many of which have been bought only once; by their creator, who just wanted a T-shirt of their own design.

And in that market, CafePress faces strong competition from SpreadShirt (http://www.spread shirt.com/), which, realising that most people want their T-shirts made for their own use, lets its customers design and ship a high-quality T-shirt straight home.

Not that these T-shirts need to be just a once-off. Not everyone is a good designer, but once everyone "can" be a designer, the possibility of uncovering a lot of good designers cheaply, just by letting them doodle for themselves, rears its head.

That's the business model of Threadless (http://www. threadless.com/), a more traditional T-shirt producer whose catalogue is nonetheless filled only with contributions from strangers. You send in a design, and others in the Threadless community vote on the best.

The top T-shirts get in the catalogue and are heavily promoted by Threadless.

The results speak for themselves - at least aesthetically. Threadless's T-shirts have a distinct look, melded by the evolutionary battles fought by its coterie of friendly, competitive designers. And while there's not much of a critical tradition for T-shirts reviews, there is Jason Cosper.

On his blog, Cosper often apologises for linking to Threadless's striking hit T-shirts so frequently, which has to be a mark of distinctiveness at least.

The truth is that T-shirts have always been an excellent model for the innovations that others struggle to introduce into other, trickier, online markets.

T-shirts have always done well on the net. They are reasonably-priced impulse items, and you know what you're getting and you know you won't be able to get it anywhere else.

I know of a few bands, and even companies, whose main source of income was T-shirt sales, and during the dotcom downturn there was much whimsical talk of the "T-economy" holding things together for many unemployed web folk.

They continue to be an internet theorists's dream product, as Cosper, CafePress and Threadless demonstrate. Infinite customisation is something that websites can provide; customer as community and contributor to your bottom line is an approach that the "markets are conversations" advocates constantly reiterate. What these sites do is aggregate many different products with individually small audiences, but a large total sale .

But lessons learnt from T-shirts don't necessarily transfer to the rest of the net. Notoriously, they don't even transfer to other forms of clothing.

Few people mind not having a fitting for a T-shirt, or not being able to see it in the store. That's not true of almost any other clothing except underwear, and perhaps socks.

Before and after the net, it was pretty easy for the average punter to come up with a T-shirt front that you'd happily wear (company outings and theatre crews have always managed it). Not true of most creative works, where a Threadless-style competition would have to work very hard to produce clothing that we'd all like.

But perhaps the comparison has failed because we're comparing T-shirts with clothing that doesn't really match. T-shirts, we think, go with jeans and jackets; blouses and overcoats.

What this is much more like is an older tradition: bespoke clothing. And sure enough, in between the T-shirts' logos depicting fake blood and quotes from video-games, a growing market for quality, unique, bespoke clothing is growing.

And it looks very familiar too. It has its hit niche blog - a Saville Row tailor at http://www.englishcut.com/. Of course, we are not all budding suit designers but we do all want customised clothes.

And there is a market that is cheap and far larger than the existing stockists can provide for: individual crafters of clothing from the developing countries.

You can commission inexpensive traditional garments from tailors in India and Pakistan via eBay. You can dig out Singaporean dressmakers who will make a perfect copy of clothes you send them, uncovered via the net.

Not as cheap as T-shirts, of course, but appreciably cheaper than you would spend in the high street - if custom-made clothes were available at all.

I really believe that the net takes what has been seen as the bottom end of the clothing market, the moribund T-shirt, and the very highest end, custom-tailored suits and dresses, and makes them close relations.

I'm only waiting for the next part of the equation: struggling fashion designers, sick of having to line up behind the big labels and cranky celebrities, breaking out on their own and selling custom-made designs direct to the public, paying Third World suppliers a larger cut, for a better deal. Then we'd see whether we had a niche, or an industry-changing revolution.