If there's something on your mind that just doesn't seem to fall into any of the other categories, well, it quite likely belongs inside Joe Finneman's marketplace. Think of it as a general store for general discussions!
I haven't seen that as a marketing tactic before! I've seen "get 17% off because it's your lucky day" because St.Patrick's Day is on the 17th and stuff like that, but not a pi day numerical sale.