Jerome Thomas, 32, is the latest of those arrivals, signing a deal until the end of the season, while the Millers have also taken 33-year-old defender Lloyd Doyley on trial.
Here we look at those free agents already at the club and assess how they have done, though that will not take long.
Leon Best, 29
The former Newcastle and Blackburn striker signed for the club during the November international break after several weeks training following a summer release from Ewood Park. He made his debut in the 1-0 win at Leeds and put in an impressive display, only to get sent off in the 72nd minute. He picked up a groin injury while serving his three-match ban and has been sidelined since, having to undergo surgery in early January.
Minutes played: 72
Stephen Kelly, 32
Kelly turned down a new deal at Reading in the summer but ended up without a club and earned a trial at the Millers. He penned a deal at the same time as Best and also made his debut at Leeds. However, he picked up a calf injury in the next game against Bristol City which kept him out for a fortnight. He returned against Hull but could only make it until half-time before suffering a recurrence which has kept him out since.
Minutes played: 179
Luciano Becchio, 32
A previous loanee, Becchio was brought back to New York Stadium by Neil Redfearn having been without a club since leaving Norwich in the summer. After proving his fitness the Argentinian earned a deal until the end of the season during the January transfer window. However, after just two substitute appearances he suffered a calf injury in training and with new boss Neil Warnock having history with the former Leeds striker, he appears unlikely to feature again this season.
Minutes played: 68
