Willie Harris-Probably the most popular option amongst the Natmosphere, but is it the right one? He's not a natural CF, and despite being fast, is not much more than average defensively. I expect Willie to get more starting time at CF, but would highly doubt seeing the Nats hand him the full-time role.
Elijah Dukes-Moving Dukes to CF gives the Nats the most flexibility, as they do have plenty of corner outfielders who can fill in at least temporarily there. Dukes is not as good of a defensive CF as Willie Harris, but the ability to have Harris fill in around the field and off of the bench may be more valuable than the difference in fielding ability.
Jorge Padilla-In a a pinch, sure. As a starter, no.
Justin Maxwell-I'd like to see Maxwell finish the year in the minors and get a grasp on hitting. He's a good fielder, but he simply doesn't have the bat yet.
Matt Murton-Adding Murton would likely shift Dukes to the full-time CF role, but I'm fine with that. Murton is a good, cheap, reliable player and I would love to see him in a Nats uniform. Kinda like a poor man's 2006 Austin Kearns.
Chris Duncan-Just like Murton, signing Duncan would probably shift Dukes to CF. Unlike Murton, Duncan is a free agent, and would only cost the Nats the pro-rated league minimum for the rest of the season (Murton was DFA'ed, giving the Rockies 10 days to try and get something for him).
My vote is for the Nats to acquire Murton or Duncan to play a corner and shift Dukes to CF, while giving Harris spot starts in CF for the rest of the year. Obviously, Nyjer being healthy would be plan #1, but that's not an option anymore.