You can say much about Doc, but beating a dead horse is not one of the things!
Where the Halloween Cameo Parties in the comic is without doubt a recurring annual theme, albeit with a couple of years hiatus, he really knows how to make the most of it without repeating himself necessarily.
There's been years where the characters from other comics arrived to the party as themselves, there's been years where characters arrived dressed up as characters from other webcomics, and finally this year where the whole cast dressed up as characters from various comics!
It's artists' abilities to renew themselves, especially with regard to the use of cameos, that makes tracking them a fun job more than a chore :)
Also, on the subject of Halloween... the Halloween Cameo Caper of 2012 has now run most of its due course and its been a regular blast to follow!
If you didn't manage to follow the crazy haphazard antics and the entwining storylines while they took place, now might be a good time to catch up. As usual all strips have been saved for posterity at the Halloween Hub, and as something new you can also follow the Caper in a sort of coninuity at the Caper's own Webcomic Hub.
Also, true to Halloween Caper Standard, there are still comics which continue their Halloween storylines past Halloween itself, so the Caper is not fully over yet!