I am a Windows Engineer by trade, working with AD since the late '98 (I worked with a major corporation that was an early adopter of the Windows 2000 BETA releases with Microsoft's blessing).

I work with Powershell on a regular basis, and specialize in AD.

I've worked for with the Fortune 500 for the last 20 years of my career. My current AD domain is 200,000 users plus (and last time I looked, about a million actual objects in multiple domains and multiple forests).

Not every project I work on however is anywhere near this large in scope. Some of the environments are only 100 or so users, so the scope of what I do varies tremendously.