My road bike has a 1 1/8 threadless carbon fork w/ integrated headset,
metal steer tube. I have a 90mm 7 degree stem and the reach seems
about right. (I've tried 80 and 100).
I'd like to get a little more height for the handle bars - I'm only
looking for 1/2 - 1 inch (~2 cm). I've tried stem flipped up and down
- there is a tiny difference, but not major.

My options are to get a higher angled stem or a steer tube extender.
Oh, I guess I could buy a new fork, but I'm not going to.

There are also two extenders that appear to be available. I'm familiar
with the ones that clamp onto the steer tube and extend upward:
http://tinyurl.com/27pr46

I recently found a completely different style: http://tinyurl.com/2gbeaz.

Basically, instead of clamping around the exterior of the head tube as
the other kind does, this one has an internal expansion plug (I guess
it's similar to a quill stem?).

The accompanying text says:

Size: 28.6/25.4
Adapter that enables you to make your steering tube longer
Does not effect the function of the Ahead system
Compatible with threaded and threadless headsets
Comes with a lightweight alloy BBB Roundhead head cap

Has anyone used one of these? Will it work for what I need?

I'm thinking I'd have to remove the star nut and place this inside the
steer tube. The expansion wedge at the bottom would connect it solidly
to the steer tube. I'd then have to set the bearings by pulling up on
it, or maybe the star nut would then go inside the extension tube?

Anyway, for $12, I might just buy one and try it, but I was wondering
if anyone was familiar with this thing.

Thanks in advance.

I've used a couple of them on bikes to replace quill stems and fit Ahead stems(basically a looks update) and found them fine. That was on threaded steerers though. I got mine from Joe at Bicycle Supply = excellent service .
Paul