The plugin you guys are talking about, at least for adminmod, was called admin_point, and it was absolutely brilliant! IIRC, the way it was used was you would bind a key to "admin_point <command>", and you didnt have to be spectating them. For example, I had F9-F12 bound to "admin_point admin_slap", admin_slay, admin_kick and admin_ban respectively. I could use these binds on anyone in my crosshair when I was alive, not just spectating. It was indispensible back in the 1.3 days when I adminned a 32-player FF server and TK'ers were rampant and no ATAC existed. Aim->SLAY, next offense aim->BAN.
After getting used to that I find that I cant stand adminning with the console anymore... this takes the console right out of your everyday admin commands, and you dont have to deal with a menu.
The only problem I remember is after first-person spectating was released, sometimes if you were spec'ing someone in first person and they were aiming at someone, whatever admin_point command you used would hit the person they were aiming at instead of the person you were spec'ing. Easily fixed by making sure you spec in 3rd person chase and put your camera directly above them pointing down before you do something like admin_ban. And it didnt always register the first couple of times you tried to point at someone, so the best way to do anything was usually with the chase-cam pointing down. Otherwise you hit the point-slay button 1 or 2 too many times and slay the next person you're spectating accidentally.