According to Forbes Magazine in 2011, the richest Football club is Manchester United. It leads Real Madrid which is in the second place by more than 400 M.
This is according to the list published in Forbes magazine on April 2011. So the list is valid till other update in 2012.
Club Value: $1864 M
Revenue Collected in a year: $428 M
2. Real Madrid
Club Value: $1451M
Revenue Collected in a year: $537M
Club Value: $1192M
Revenue Collected in a year: $336M
4. Bayern Munich
Club Value: $1048M
Revenue Collected in a Year: $396M
Club Value: $975M
Revenue Collected in a Year: $488M
Similarly Milan held the 6th place while Chelsea, Juventus , Liverpool and Inter Milan secures 7,8,9 and 10th place respectively.