Seems like it would be more accurate if it were based on their profile page and the "created X days ago" bit.<p>Once you've grouped by day you could then look at participation to provide a little more granularity over the course of the day (put everyone at 23:59 on the day and if a bit of participation can proven to have been earlier in the day move the person to that time).<p>Then the chronological result is your list and a better indicator of the potential userid.<p>Not that I think this is accurate, I run a community that does use userids and when you account for the accounts deleted because they were spammers you end up with a sparser set of users. Someone isn't the nth person on the site, they're just the nth id allocated by an autoincrement counter.<p>The utility is a little pointless though. Whilst a userid is one of a number of useful metrics of social status (ah, an early member! or ah, a n00b!) on their own they are pretty useless.<p>You do need to put these metrics in context, they're useful when you're on slashdot because they're visible as part of the comment stream so you can factor them in to your reading of the comments  and easily compare the various indicators of authors visually.<p>If the function to get the metrics is elsewhere and not easily comparable, the usefulness as one of a collection of metrics is far lower than if it were visible.*<p>All that said, I prefer the equality of usernames. I like the precept that "time registered" isn't a major factor and that your words and thoughts are worth more than just having signed up early.<p>* Perhaps you want to make a greasemonkey script?* *<p>* * You could do one for tagging too so that tagging over there is transparently part of the site here.