On top of the daily stats on the front page HT mentioned, which shows somewhere between 140 & 180 visitors daily, there are other stats. The following shows how many people are active (those who take the time to login, rather than browse without an account).
Active Members 7 Days: 286
Active Members 30 Days: 532
Percentage wise these are actually quite high for a forum, as a lot of forums knowingly have inflated/invented member counts as they don't take such proactive measures to stop illegitimate account registration, or spammers!
As the visible stat counters are a value held in an SQL database table, it's incredibly easy to make a forum look more active than it is.
Our registration SPAM counter measures block a set list of countries from registering (you can probably take a guess as to which ones those are!). As a backup it also checks the username & IP address against known SPAMMER blacklists, and flags them for manual checking.
This means that I would say almost every account that's been created in the last couple of years is a legitimate human with some interest in BMW Zeds. If I spot something that comes through, then the account is deleted - which then feeds the details back to the SPAM blacklists and helps other participating forums reduce their SPAM.
Activity is an odd statistic to measure or quantify anyway, as a lot of "active" users may on read and not want to contribute.
Removed all off topic posts from this thread as well!