A transfer ban was imposed on three clubs by the Football League on Monday, but it does not stop them adding players in January.
The number, and quality of players without contracts at this stage of the season is typically thin-pickings, but here are five possibilities for the Championship clubs.
A former England international, Jenas is a free agent after his contract with QPR ran out in the summer. He has been in rehab due to a knee injury sustained in April and is thought to be closing on a return to fitness. He's exactly the sort of experienced midfielder Leeds need, but Forest could hold an advantage due to his previous connections with the club.
Dickson Etuhu remains without a club after being released by Blackburn Rovers in May. The former Fulham midfielder had a tough time with injuries, but with time to focus on getting fit, perhaps the 32-year-old will have got himself back into shape to revitalise his career?
Nottingham Forest had Mikael Leigertwood on trial in the summer and decided against a deal, but considering the ban, could they seek to revisit their interest? The 32-year-old has made more than 400 appearances in English football, and could also provide the experience Leeds need if he can prove his fitness.
Once a highly regarded Liverpool prospect, Nemeth's career is in a slump at only 25, stuck without a club after leaving Dutch team Roda JC. The Hungarian international striker has been linked with a move to Major League Soccer this month, but could yet be tempted by a Championship side.
Former Leeds loanee George McCartney is a free agent after leaving West Ham in the summer. Blackburn have had injury problems in defence over the last month, and the 33-year-old could provide an extra option for Gary Bowyer's men.