There are of course some "canonical" big FreeBSD users, but I wonder if there are more? It looks like it there may be some big FreeBSD installations in Eastern Europe and Russia (judging from postings on forums and mailing lists) but apparently they don't advertise it much (I might be wrong).
As for myself, I'm also in Eastern Europe and have spread FreeBSD on a scale I could - mostly in the academic and government environments but the number of separate installations is around 20-30, which I'd consider "small" on a global scale.
I'll make a patch for the page if there are any interesting comments here!
Update: luckily, one of the first posts mentioned the Commercial Vendors page and the whole "Vendors" section of the web - so it might in addition to all I said: check that page to see if you are listed! :)
Update 2: thank you for all your reports! But could you make them in a form which is quotable on a web page or in documentation? For example: start with the description (and a name if possible) of your company, describe in short what the company does and what you use FreeBSD for, why do you like it, and if possible end with a recommendation. For a very funny and unrelated random googled example of what I mean, see here! :)