Items of ritual:
I personally collect unusual dice, and I have a ritual to finding dice that like to roll 20's.
I always like to, build a mini for my character. ie games workshop. (there are other makers of these figures, but the round bases from GW are perfect.)
Game Mats, all hail the hex pattern game mat.
Rituals observed:
I have two videos I must watch before any new game.
Stephen Lynch:
http://www.youtube.com/watch?v=QgOB7VWjlSQ
Dead Ale Wives:
http://www.youtube.com/watch?v=vChEPj0dXXk
After the game has started I have a dice ritual for finding dice which will be used that day.
I roll all my (30 of them) d20's any d20 that rolls 15 or greater I keep, then I roll all these any of the d20's roll 16 or higher I keep, usually this leaves me 3 to 4 d20s for the game.
Sacrifices during D&D:
It use to be Mt. Dew and Pizza, although the last campaign it had become Monsters and Bacon Wrapped Hot Dogs.
---------- Post added 2012-09-15 at 11:59 AM ----------
I should point out if they are playing Pathfinders, Iron Heroes, Exalted, Champions, White Wolf, Classic TSR, Cyberpunk, D20, GURPS, or any of a long list of games They are all known as D&D to the unenlightened. To the enlighten you can call them Pen aNd Paper(PNP) or Table Top RPG.