Actually, there's a thread somewhere here in Office Party (you may have to search back a number of pages) specifically for people to celebrate every milestone that they find important.
I believe it's called "Post Count Milestones" or somesuch.
And yes, AW is a very addictive site. Especially as when I first came here, I knew nothing about the industry or business of writing, editing and publishing, and didn't know any of the key words for describing how I write or how others write and which I'd like to emulate.
I still don't know half of it, but the site has been incredibly useful, and it really is a fantastic place for any creative person. It's tailored specifically to writers of every kind, but there are sections you can go to if your interest is visual art, music, moviemaking, whatever.
(And I'm sure you'll hit 10,000 posts in no time.
)