I've been looking at steemian.info where you can see up to 400 of the witnesses (active and inactive). Something like that on Steemit would be extremely useful, even if it was shortened to the top 250 which would encompass all currently active witneseses (unless there's a bunch below 400). It would also be nice if people would withdraw their upvotes for inactive witnesses, so there wasn't so much clutter within the lower tier group, but I guess that's all part of the ongoing 'fun' of a decentralized system where anyone can be a witness for life, active, contributing, or not. :)