Ok, so people all over the interwebs are making these mason jar lights, and they're so cute I finally couldn't stand it any more (who are these people, you ask? some of them are here, and here and here...)
secretpocketblog, and I suggest you do the same. If you can find vintage, or colored, jars, that would be really cute, but I just used regular mouth quart canning jars by Kerr, which I got at Smart and Final. I then went and got cord components from Ikea ("Hemma". unfortunately, they force you to buy a lightbulb you don't need with it, but oh well). The lightbulbs I used here were display bulbs (found easily at the drugstore)- 40W clear Showcase/tubular bulbs.
The basic idea is simple- you trace the outline of the circle where the lightbulb screws in onto the flat part of the jar lid. Then, you use a hammer and a flathead screwdriver (on top of a board, or something you don't mind the screwdriver punching into) to punch out the circle. Stick the fixture through, screw on the bulb, screw on the jar, and you're set!
I felt like the light was a little industrial for my living room (although it would be great over a desk or workspace), so I used some fabric I had sitting around and wrapped it around the jars and glued it with a glue gun.
The light these put out is so nice and warm (without actually seeming like colored lights, which might be a little much) and the curves of the glass make light patterns on the ceiling. I love them! (note- it is REALLY hard to take a good picture of a lit lamp, turns out, but these at least get the general idea across).