I know that it is possible to make your own pinhole, but do lens manufacturer's make pinhole "lenses" that include aperture data, etc? If so, who makes them?
A company called Rising makes a precision laser cut pinhole lens based on the body caps for various makers, including all the dSLR makers. Included in the documentation with it is the focal length and aperture, but it varies a little bit by body because of the distance from the hole to the sensor. On the Pentax, for example, it's 45mm and f/204.
At any rate, I can't find their website, but if you Google "rising pinhole cap" and camera maker you want it for, you'll get a ton of hits. As far as I can tell, they are available in Australia.
I have one, at any rate, and it's kind of neat. You get some interesting effects with certain kinds of lighting.
Photojojo make a pinhole "lens" for Canon and Nikon, it's f/181 but is not chipped so you won't get aperture recorded in the EXIF data.
Although Canon surprised everyone recently by releasing a pancake lens I can't see them coming out with a pinhole!
I've been very happy with my Skink pinhole and zone sieve. They are very high quality parts and work very well.
You can read about them on their website, they use ebay for sales and I'd reccomend them to anyone interested in the subject. What's really nice is that you get to try different inserts, pinhole and 2 different zone sieves!
Here's one of my shots: