The plan is to have a nice prominent MEM logo, alternative themes will also be considered.
Rather than make the decision for you - please feel free to go to the SMF themes website,
http://custom.simplemachines.org/themes/, have a poke around, and when you see one you like - let me know and I'll get it downloaded.
Eventually, I suggest we settle on 2 or at most 3 themes (other than the defaults), otherwise whoever wins the forum logo competition is going to struggle to keep up