As Paul mentioned in his post on Flight Club earlier today, the tower at Wittman Regional Airport in Oshkosh, WI will again hold the title of World's Busiest Tower next week as 10,000 or so aircraft descend upon the field for AirVenture 2014.
One of my favorite parts about AirVenture is listening to the ATC as it happens. I even go so far as to download mp3 archives of the week's ATC so I can listen later on when I need an "Oshkosh" fix.
What makes the situation so unique at AirVenture is that there is such a huge volume of traffic, with communication between the tower and aircraft usually being one-way. On top of that, during high volume times, they are landing multiple planes at a time on the runway. To facilitate this, there are evenly-spaced colored dots painted on the runway as markers. You'll hear the tower say something like "high-wing Cessna, turn your base now, cleared to land orange dot."
"Dot" is a bit of an understatement.
What it amounts to is a virtual conveyor belt of aircraft lining up, landing, and taxiing.
If you want to hear a sample, I've posted a bit from last year here, courtesy of LiveATC.