Many of you are probably scrounging around for replacements for David Ortiz (good luck) and Ryan Zimmerman (more possible). Ortiz is gone for at least a month, maybe longer, and who knows whether his wrist injury will sap his power when he returns. Zimmerman's status on the 15 day DL is a bit more nebulous.
Hurler favorite Jorge Cantu might also be out there, but probably not. Jason Giambi had a great May, but I doubt he's a free agent. Matt Stairs: also probably not available. Kevin Millar? Ugh.
Perusing the waiver wire, Bill Hall, the suddenly resurgent Pedro Feliz, Melvin Mora, and Casey Blake seem like the most plausible 3B replacements available in mixed leagues. (If you had Ortiz in AL-only leagues, forget it -- you're fucked). Of those, Blake is currently playing the best, and he's useful at multiple positions.
Corner infield power is tough to find.