the sea-me thing has a little visual indicator add-on that you can buy. it's close, but not quite the same. it is, however, the closest i've seen to the c.a.r.d.
the c.a.r.d. has an optional audio alarm, and visually shows which direction the radar signal is coming from.
this system is passive, which sucks, but sometimes seeing the ship is enough without them seeing you.
i like how the sea-me is active, and makes you seen better.
i've also heard you can make a passive radar REflector using hundres of lightly crumpled strips of aluminum foil, in some kind of receptacle, fixed as close to the masthead as you can, without it chafing a lot on the leech of your jib.
i have not tested this, however, i would like to experiment a little more. i have just been told it works great.