Not for seat availability (Y9 K9 ...)

Is there any tool currently available to see which seats are available on a flight? I seem to remember seeing one of orbitz/travelocity/expedia with seatmaps, but didn't see it today.

Usually I've been flying CO and using CO.com, but now I have a bunch of flights on AA/US/UA.

Thanks.
Mitchell

P.S. I searched the archives on seatmap, and couldn't find anything relevant. Many of the old threads on "seatmap" were closed, citing lots of other threads, but most of those seem to be about galileo-seat availability tools.