These are simply based on things I've heard over the last few weeks. It doesn't mean they're going to happen, but it does make for good discussion.
Right Wingers:
Michael Ryder - New Jersey Devils: $3.5M UFA RW The Caps have been getting some decent depth scoring from their second and third lines the last few weeks, but the first line solely depends on Alex Ovechkin. So far this season they have used 8 different players with Ovechkin and Backstrom, and so far no one has really stuck out. Marcus Johansson has been playing recently, but if the Caps don't get a proper second line center, then Johansson would be the best option in that role. The Caps could look to Ryder and get him pretty cheap. He may only cost a second or third round draft pick, or the Caps could even offer up Jason Chimera. Ryder would look pretty decent on that right side. He could re-sign for a good price.
Drew Stafford - Buffalo Sabres: $4M UFA RW Another good option for the first line. Stafford will most likely be another draw for teams looking for a little more punch come playoff time. He'd be a rental at $4M, but Buffalo might retain some salary to make a deal more juicy. The Caps could even trade his rights at the draft like they did with Halak.
Left Wingers:
Evander Kane - Winnipeg Jets: $6M through 2017-18 Believe it or not, the Caps and Jets were talking trade until Kane opted for shoulder surgery. He's a crap shoot at this point, but being stuck in Manitoba can make any one crazy. He has the potential to score 40 goals a year, and once his maturity level evens out, he'll do just that. He's also very expensive for the Caps and they would have to get creative in the off-season if they still want to pursue him. For now things will be quiet, but the Caps might still be interested for next season. He'd be a nice second line option or see some time with Ovechkin and Backstrom if Ovi slides over to the RW.
Centers:
Antoine Vermette - Phoenix Coyotes: $3.75M UFA C Vermette will most likely be dealt, and chances are the Caps are not in the mix anymore as they were earlier in the season. However, he a viable option to fill in that second line center role, and would good with Brouwer and Kuznetsov. The Caps would have to clear a little more cap space however. Not sure if they'd be able to re-sign next year.
Brad Richards - Chicago Blackhawks: $2M UFA C He's an interesting case. Richards has been OK for Chicago this season, but hasn't been consistent enough and a trip back to the East may be in order. The Blackhawks probably won't trade him, but if a good enough offer comes up, they may be interested. He doesn't cost much and is still a great playmaker. Come the offseason, he may take a similar deal with another team and the Caps should at least kick the tires.
Jiri Tlusty - Carolina Hurricanes: $2.95M UFA C A cheaper option for the Caps would be Tlusty. It's been a long season so far for the Tlusty and the Hurricanes and the re-tooling or re-building process will begin soon. Tlusty may cost a couple draft picks or a young prospect. He's a sneaky scorer, kinda like Semin, and could do well with a change of scenery. The Caps would probably just rent him.
Mike Richards - Manchester Monarchs/LA Kings: $5.75M through 2019-20 C That contract is brutal, but it doesn't mean it's not manageable. Richards, in my opinion, is the best option for the Caps. He's been stuck on the 4th line in LA and hasn't been able to play his game this season. He still has a lot to give and now wants a second chance to prove it. The Kings could retain some salary this season, but the Caps would have to get creative in order to bring him on. Mike Green is the best bet to the other way, plus it would get Green out of the East, which I think is exactly what the Caps would want to do anyway if they trade him.
Patrik Berglund - St. Louis Blues: $3.7M through 2017-18 C Berglund hasn't had much success this season, and the Blues need to clear some cap space. He's a solid two-way guy would plays a great Western Conference type game, exactly what Barry Trotz likes. He'd be a nice fit and could be a nice option for the next few seasons. He's more realistic an option than Vermette and would cost less to get.
Goaltenders:
Viktor Fasth - Edmonton Oilers: $3.4M UFA G The Capitals backup situation is an interesting one. Justin Peters has clearly fallen out of favor for in DC, and Philipp Grubauer has only proven effective in one game. If the Caps want to continue playing well, they'll need a reliable backup to give Holtby a night off or two. Fasth could work out, but he is expensive for a backup goalie. Also, would it be worth it to give up assets for a him?
Michal Neuvirth - Buffalo Sabres: $2.5M UFA G The Caps could look to bring a familiar face. Neuvirth hasn't done much in Buffalo and they could look to move him out for a draft pick. He wouldn't compete with Holtby at this point and he could get better support from his team because of the familiarity. He's a free agent at the end of the year, and the Caps could just let him go and call up Grubauer for next season.