Guys like Rick Nash, Derick Brassard and Gilbert Brule are presumably untouchable.
Columbus will likely trade unrestricted-free-agents-to-be Anson Carter and Bryan Berard before the February 27 trade deadline, but I doubt the Caps would have any interest in renting either (besides, if "fool me once" is shame on you and "fool me twice" is shame on me, what would it be if the Caps took Carter a third time - shame on the fans?).
Despite occasionally-strong play from Fredrik Norrena, I doubt the Jax are looking to move goaltender Pascal Leclaire (though if they were, I'd think it would be a great move for the Caps to go after him).
So that leaves the obvious. Nik Zherdev has been a problem child for Ken Hitchcock, but he has far too much talent for the team to give up on him at this point (and already signed at $2.5m next year and $3.25m in 08-09, Zherdev is a bargain for the offensive talent he brings to the table). And despite the "he's Russian, the Alexes are Russian, therefore he'd be a perfect fit in Washington" line of thinking, I'm not sure that taking on someone else's prima donna headache is really what the Caps are looking to do right now. Still, sniffing around Zherdev is just about the only thing that I can think of that would get two or three scouts out to Columbus, Ohio in the middle of February. Then again, I'm not in scouting so what do I know? What do you know?