I must admit I am a huge fan of doorstoppers, as far as literature goes, and it translates into a distinct preference for longer (though not endless) manga as well. I'm probably not the only one, and conversely, I can easily imagine someone preferring something relatively short. One-shots are already covered as a genre, but for everything else, BU could take advantage of the "Status in Home Country" section of the series pages. (Only looking at tankoubon volume count, for consistency.) A search field could just be implemented as "_____ to _____ volumes," with both blanks optional so that people can search with an upper limit, a lower limit, both, or neither.

i second this!