I've been using Random (java.util.Random) to shuffle a deck of 52 cards. There are 52! (8.0658175e+67) possibilities. Yet, I've found out that the seed for java.util.Random is a long, which is much smaller at 2^64 (1.8446744e+19).
I have a bash script that starts many client processes. These are AI game players that I'm using to test a game with many players, on the order of 400 connections.