I'm at a desk, 8+ hrs a day. Are there ANY exercises I can while at work that can strengthen..uhm...ANYTHING on my body?

Kegels!!

Maybe you could purchase some small handweights (2-4lbs) and lift those while on the phone.

I've done calf raises under my desk. I also get up every so often and do a quick walk somewhere in the building. Another idea might be to walk up & down stairs on a break. It doesn't sound like much, but done a few times throughout the day must burn a little bit of calories and gets the blood flowing! : )

I also walk around the building 2x on each of my three breaks. I figured that 6x around the building is probably a mile.

Do some sucking in the gut and tucking in the butt exercises. Or something to that effect.

Look into isometric exercises. They are surprisingly tough, and a lot of them you can do fairly surreptitiously. Another thing I like to do, though maybe not exactly an exercise, is to practice my yogic breathing. Strenghtening the old diaphram.

And yeah, kegels -- anytime, anyplace. Work, stoplights, waiting in line...something devilishly fun about looking someone in the face while doing those.