Sometime around now (it’s not a statistic we keep an eye on daily), we will pass 100,000 unique bug reporters in bugzilla.mozilla.org. To try and give you some sort of handle on that, this is approximately equivalent to the entire population of Chelmsford (UK), Cambridge (Mass., USA) or Cairns (Australia) each filing at least one bug. (Submissions of other correctly-sized cities in your country welcomed in the comments.)
Other interesting stats: our average-bugs-filed-per-day has gone from about 70 to 119 over the last year, and there are currently 294,115 Bugzilla user accounts.
Occasionally people complain about the cryptic nature of the Bugzilla UI, and we have done things to address it. When considering that question, there are two ways to look at these stats. Either, “if 100,000 people can work it out, we can’ t be doing too badly”, or “if only 1/3 of account creators successfully file a bug, then our UI is too complex”. The latter view, of course, assumes that filing a bug is the only reason that people create accounts. How solid is that assumption, I wonder?