My number is bigger!

"My number is bigger!" is a contest held in a discussion thread at the xkcd forums. The thread was begun on the 7th of July, 2007, and it currently contains 35 pages (40 posts each).

The goal of the contest is to come up with a computable, finite, well-defined number bigger than the last poster's number, by using already established numbers and notations (such as Graham's number and xkcd number) and without referring directly to the previous number.