Good question Tippy... I was wondering the same thing. FWIW I've notice 2 reoccuring things in my hacklog file:
1. When AOL users complain stuff dont work or they get lots of page timeouts, I can always find it in hacklog.
2. Most WebTV users cant seem to register, and the registrations that never get to the queue are in the hacklog file. I say "most" because I have 5 WebTV people mighty upset they cant get registered, yet I do have one other WebTV user who says he got in just fine. I even put one of the folks having trouble in touch with the guy who got in just fine and they couldnt figure out why one worked and the other didnt.
but other than this stuff... there's other junk in my hacklog file that makes me wonder what the heck it is.