I’ll start with the 3D scanner since it seems a lot more ergonomic than the 3d printer. It only requires a webcam and a laser pointer. Very interesting. A nice alternative to spending thousands of dollars for a professional 3D scanner, if you need to transfer something into a 3D file.
http://www.youtube.com/watch?v=w2uH1Ag2cAY
The quality doesn’t look that great, but I’m sure you can get better quality with a higher resolution and better quality webcam.
This is where it gets interesting, though. Imagine a 3D printer you can make for around only 500 dollars. Compared to the commercial 3D printers, this would be a very cost effective solution to home printing.
Reprap is a feasable in-home 3D printer that is self replicating, to an extent; it can produce its own plastic parts for replacement or for a friend. It can print most 3D models from model files on your computer, using a filament (thread) of material (such as ABS plastic) fed through a melting chamber using an extruder. The liquified plastic is then pushed out the other end as the write-head is moving, thus creating a plastic replica of the model, one layer at a time. The nozzle size of the extruder can vary, but .5mm is common, and .3mm is sometimes used for finer quality models. The cost to buy all materials is estimated at around 500 USD and creates fair quality models. After that, all models it makes cost only what the raw materials cost. This project is interesting in that it is open source. It is headed up by Dr. Adrian Bowyer of the University of Bath in England. The current generation is called “Mendel.” It is the second generation of the RepRap. Here are some links if you are interested in following this project.
Wikia:
http://reprap.org/wiki/Main_Page
Printing a chess pawn:
http://www.youtube.com/watch?v=B6B8WgTOv_A
Early tests with printing solder, meaning it may be able to print its own circuitry in the future:
http://www.youtube.com/watch?v=Wnu4lmOnX00
of course, with the size of those channels, the chips would be much bigger. Imagine a microprocessor printed like that. O.O It’d be huge.
Interview with Adrian Bowyer:
http://www.youtube.com/watch?v=FUB1WgiAFHg
Introductory lecture:
http://www.youtube.com/watch?v=TZfcETkbGWk - part1
http://www.youtube.com/watch?v=S8cUJowU5OQ - part2
Some of the concepts he puts forth in these are a little bit far-reaching in that I don’t believe it’s realistic to expect it to change the world or anything like that; there are only several thousand Repraps that have been made so far.
Homemade legos, anyone? 
Let me know what you guys think. This is very interesting to me, and I may even try to build a reprap in the future, although looking the wikia “how to build” guide, it looks like the circuitry and everything would give me a headache.