Who?
If you've got a brilliant idea about to be bought by everyone and fundamentally change the sustainability of the world, go ahead and spend a bunch of time raising venture capital and patenting things before you let anybody buy this.  If you care about getting your idea out there and built while maybe earning some beer money, you might find Dirtnail interesting.

What?
Dirtnail is a place to buy and sell the many products in the middle, those things for which demand is more than one but fewer than enough to quit your day job.  

Where?
Distributed:)

Why?
Practical Answer:
Let's say I want a laser pointer strong enough to pop balloons from across the room.  Traditionally, I have 2 options:
  1. Buy the commercial version: ~$500+ and 10 minutes
  2. Build my own from a DVD burner: ~$50 and, depending on my skill or lack thereof, several to many hours.
So, lots of money and little time or little money and lots of time.  Shouldn't there be a middle ground?  If only there were some way to facilitate buying one from  somebody who's already built one, I'd happily pay them $200 for their trouble...
I want Dirtnail.com to facilitate this.

Philosophical Answer:
Innovation in the modern world is more than a bit lacking, and that's a very bad thing.  Also, we're screwing up our world and our bodies by sitting around buying all this resource-consuming stuff instead of getting up and making something cool from the free junk in our neighborhoods.  Hopefully, the opportunity to earn beer money making things can spur a little more innovation.  

There are many people much smarter than me making this argument far more eloquently:
When?
Please don't email me complaining about the lack of cool products available.  I would, however, like to hear about:
  1. What you want built (to what spec and how much you'd pay)
  2. What you have built (to what specs and for what price)
I also don't want to hear about liability.  Halliburton doesn't worry about it, so why should we?

How?
Get building!  Inpiration for many lifetimes worth of projects can be found at Makezine and Instructables.