An Unmanned Aerial Vehicle (UAV, colloquially known as a "drone") is basically an aerial robot. As we define it, it is capable of both remotely controlled flight (like a regular RC aircraft) and fully-autonomous flight, controlled by sensors, GPS, and onboard computers performing the functions of an autopilot. Our UAVs include airplanes, helicopters, quadcopters and blimps. Most of them are under five pounds, and some of them (especially the blimps) can be used indoors.
We are focused on non-commercial ("recreational") projects by amateurs, although pros are always welcome too. Reasons to make your own UAV range from a fun technical challenge, student contests, aerial photography and mapping (what we call "GeoCrawling"), and scientific sensing. We are primarily interested in civilian, not military, UAV uses here.
If you're new to all this, start here.
DIY Drones is a community based on the Ning social networking platform, and anybody who registers (it's free and easy) can post their own blog entries like this one on the front page, along with starting discussions in the sidebar at left or uploading videos below that. Your registration gives you the ability to do a lot on the site--so feel free to post anything you think will be of interest to this community!
There are other amateur sites out there, from the discussion forums of RC Groups to individual blogs, but DIY Drones is explicitly built as a social network, which means that the community is as important as the content. We're also focused on the most accessible end of the amateur UAV world, with the aim of potentially including high school students.