One theory I've heard for Marleau would be to wait until July 2nd, and pay his $3M signing bonus. Then trade his full contract to a cap floor team, like Ottawa or Arizona, etc, along with another pick or prospect.
That team buys out the contract, which would only cost a shade over $400k. The $6M cap hit would only be for next season.
Marleau can then re-sign in Toronto, or San Jose or wherever else he wishes. Could give him $1.5M which is more than his base salary for next season anyway.
Leafs would save $4.75M in cap space, or the full $6.25M if he goes elsewhere. Marleau would make another $250k for waiving his NMC to facilitate it, and the other organization would get a pick/prospect for $415k.