It's http://publicbackup.com/shared/flyertalk/availability/ for one version - It really isn't that precise since most airlines show a maximum of 9 but could be much higher than that - only accurate if lower than that. Example - USAirways 748 - Charlotte to Philadelphia for 8/14/07 - right now shows (F5 A5 P5 Y9 B9 M9 H9 Q9 N9 V9 W9 L9 S9 T9 G9 K9 U9 E9 R9) which basically means wide-open.