The difficult part of making a site like that is getting customers: Actually programming the site is quickly done. The reason Joel's jobsite works is because t

The difficult part of making a site like that is getting customers: Actually programming the site is quickly done. The reason Joel's jobsite works is because they already have a lot of smart people coming to the site, and can push them on to the job section. So in answer to your question: Yes, if it isn't out there (and since you've looked and haven't found anything it seems like a good presumption) it's a good idea. But don't kid yourself - marketing the site is at least 2/3 of the effort. And if your original problem is that it's hard to find customers this may not be what you want.