Hopefully your fantasy league already has something set up, but if not it's time to start thinking about postseason fantasy football. Just because the NFL season has ended it doesn't mean you need to lose your fantasy football fix. The NFL postseason is a great time to get in some more smack-talking fantasy competition.
There are several different ways to set up a postseason fantasy league depending on the way your league is set up and the options your commissioner service allows. I play in a league where we keep all our season rosters during the playoffs, with a giant waiver wire rush before the playoffs to drop guys like Willis McGahee in order to pick up guys like Heath Evans. We assign a bit of prize money from the pot to the winner of the league "Pro Bowl" (as we call it) and have a lot of fun tracking it through the playoffs.
Another way to do it is to clear all the rosters and have a new draft from a pool of the NFL Playoff teams. This is usually more fun as every team has the opportunity to get Tom Brady or Peyton Manning. This is limited by your league's ability to have another draft though, so if you're all playing in an office league this may be perfect but if you're playing on the internet from ten different locations the logistics probably eliminate this. Your commissioner service may also not allow you to clear rosters and have another draft; Yahoo's service is notoriously inflexible this way.
You can always change your league rules and come up with something even simpler if you like. For example, set five player rosters to 1 QB, 2RB and 2WR and use simplified scoring by only counting touchdowns. Or you can only count yardage. There are lots of different ways you set up a postseason league. However you do it, I recommend getting started now on your postseason fantasy football league. Fantasy baseball may be on it's way, but fantasy football owners don't have to let go of the spotlight just yet.