A friend and I were sitting in our cubes at work and trying to create the greatest bounded number we could using only a few characters.
We came up with $A(G,G)$, which is the Ackermann function with Graham's number $G$ as the '$M$' and '$N$' variables.
Beyond the fact that this number, though technically a bounded number, seems absolutely unquantifiable, are there larger numbers that we missed?