I plan on starting one soon for a project my wife is spearheading. It will be ready for a network install of WordPress of course. There will be theme options to change many settings, & it will be translation ready.
It will be suited for a full site not just a store (that's what my needs are).
If there's a need I'll put it for download somewhere - probably free for a limited time & then a reasonable charge. What would be a fair price?
I haven't done a multisite project with MarketPress yet, so what are some key features that you'd like to see in a theme?