That being said, I have been roaming around the monastary for a while and had never even heard of this.

Indeed I also found it on a more or less random basis, not really in the CB, because I have it disabled. I actually don't even remember where, but probably I must have seen the XP chart in some other monk's homenode and wanted it for mine too. So I had to search for the very beast, and actually once you know that it exists, then it's not that hard to find...

I was wondering why this site isn't advertised more. Is there any reason in particular? If not, why isn't it on the main menu or at least a default on the side bar menu?

Because, as you notice, it's hosted at another place:

errol:~ [11:07:32]$ host perlmonks.org
perlmonks.org has address 209.197.123.153
perlmonks.org has address 66.39.54.27
perlmonks.org mail is handled by 10 mail.egl.net.
errol:~ [11:07:39]$ host tinymicros.com
tinymicros.com has address 65.6.151.62
tinymicros.com mail is handled by 10 tinymicros.com.
[download]

Indeed it's not really a feature of The Monastery, although it collects statistics about it: it's really a side project. Just as perlmonk.org, which I found by noticing that some authors occasionally referred to their homepage there, and indeed at first I didn't notice the missing "s", thus thinking it were a PM feature. (And I wanted one too.)

Perhaps, a permanent list of PM side projects would be fine. Currently I don't know if one exists, but if so, then it mustn't have too high a visibility. However periodic announcements are done, e.g. wrt perlmonk.org's "downage" and return to life.