Ubuntu Black or Extra Bold

Hello Matt, thank you for the question! The answer is probably much the same as for similar questions such as "will there be an Ubuntu … XYZ expansion?". It's highly dependant upon somebody, such as yourself, taking it foward. The following answer hopefuly covers the background:

  "Will there be an Ubuntu Serif font in the future?"
  http://askubuntu.com/questions/26104/will-there-be-an-ubuntu-serif-font-in-the-future/26995#26995

For an extra bold, rather than for a serif-style, it should be easier, as one could interpolate from the existing proportional weights, to get starting points; before the type-designer then sets to work.

It would be a good idea to clearly know the use-cases; what's it going to be used for? The thirteen weights that Dalton Maag have been working on are formulated from expected needs. Another question might be how much Unicode coverage is needed; and covering which script-systems and languages?

If those are hard to answer. Perhaps do the same for a much thinner weight (an Ubuntu Thin, perhaps). Thin might work better for huge outdoor and poster sizes, than an ultra heavy.