Does this exist - Expresscard w/ HDMI output (for laptops)

[RU482]

I am looking for a device that plugs in to an expresscard slot, and provides an HDMI output.

Does such a thing exist?

 

[PCTC2]

Yes and no.

Matrox has an ExpressCard breakout box that costs around $500.
Asus had the XG station which allowed running a desktop graphics card from your ExpressCard/34 slot. VillageTronic has a similar product now (ViDock 2).
If you have a DVI and Optical-Audio-Out capable laptop, you can buy a TOSLINK/DVI to HDMI adapter.