What is the busiest (most players) minecraft server that is still online?

Minetime (ip is Minetime.com). It is pretty busy to me as it has thousand of players online.

A server called The Hive gets from 2000 to 4000 a day. The Server ip is: hive.mc.eu.

Shotbow.net
I really like shotbow, there's usually at least 2000 players online, but i usually see it at 3500 players. Most i've seen shotbow have is over 5000.

Hypixel has over 11,000 players on right now:

Here's a review of what games the server has on it -- it's actually a lot of fun.

http://www.myminecraftservers.com/minecraft-server-review-mc-hypixel-net/