The Mac Game Store has some deals up.
Call of Duty: Black Ops $25 (Steam)
Call of Duty: Black Ops – Annihilation & Escalation Content Pack $12.49 (Steam)
Call of Duty: Black Ops Rezurrection Content Pack $7.49 (Steam)
Omerta – City of Gangsters $10 (Steam)
Omerta – The Japanese Incentive $5 (Steam)
Rocksmith 2014 Edition $24 (Steam)