Achievement Dead Man's Hand In Army of Two put me at exactly 25,000 achievements popped
That's a lot of popping! It roughly comes out to 12 achievements popped per day since the release of the Xbox 360 on November 22nd, 2005. I might come close to hitting 50,000 achievements one day in the distant future but no one will ever hit 100,000. Not a single person anyway. 100,000 achievements would put you well over 2,000,000 gamerscore.