See instantly beautiful product pages.
Indeed it would be nice. Hack, Midnight and Time-machine are (I think) the most appropriates themes for OMZ :)
I'll vote Midnight.
Midnight and Modernist both look really nice.
Have to agree with @ColinHebert on this one.
What Prezto features would you advertise on the product page?
I think you should start listing the main modules (syntax-highlighting, history-substring-search, completion, prompt). By main I mean modules that will probably be used by everyone and are often a PITA to set up manually.
Explaining that prezto is mostly about setting the sensible defaults (some examples of default settings that are not sensible), but also about adapting to the user's environment (gnu-utility, osx, tmux/screen, git, etc.).