I was recently the subject of a photo shoot featuring a "Pillcam SB2".
This is a gizmo the size and shape of a large pill; it contains a color
camera which takes two photos per second, a radio transmitter, and 8
hours worth of battery -- total weight under 4 grams. See
http://tinyurl.com/5szgym for info.

I retrieved the camera (don't ask) and would like to have some fun with
it. These are considered single-use items, but I'll bet if I pry the
sucker open and replace the battery I can make it go for another 8
hours. Seems like it might be neat to hang under one of those $25 micro
helicopters. Plus they make another pill that does 18fps -- maybe they
use the same controller for both, and just change a jumper...

In normal use, they stick a bunch of patches on you. Each patch
contains a circular antenna about 2" in diameter. The maximum distance
from the pill to an antenna is probably around 18 inches. I'm hoping a
larger RX antenna might be able to gather enough signal to allow a range
of maybe 25 feet. I'd be able to play with the antenna on the TX side
as well -- I'll bet 11mm doesn't allow for an optimum transmit antenna
in the pill.