At this point in the game, there aren't a great number of options. There are two recently released HD D-VHS recorders, one from JVC and one from Mitsubishi, but both have FireWire inputs for HD video, and as yet, there's almost nothing that you can buy which will supply HD video to them through this connection. There's a company called Sixteen Nine Time (169time.com) which modifies RCA DTC100 STBs to give them FireWire outputs, but these can only be used with an old Panasonic deck that can no longer be purchased.
There are companies which make PC cards which will tune OTA HDTV and record it to disk for later playback. I don't think that anyone's actually making these into off-the-shelf systems, so you'd have to roll your own. One of the companies making these cards is Telemann (see a brochure for their Hipix 200 card here) and Hauppauge (a brochure for their WinTV-D product is here).