Groupon

The idea of a group discount is great, but you don't get to exploit it regularly -- how often do you bring 25 guys to a strip club, or bring 25 kids to the aquarium? Get group discounts you can use, from Groupon

From the guy behind ThePoint.com, Groupon's a daily e-blast offering the masses one exclusive & heavily discounted deal per 24-hour window, like a giant soup of the day, and everyone gets a spoon. To take advantage, you prepay the stated rate, but you're only charged if a predetermined amount of other users do the same -- basically, enough that the deal makes sense for the business, establishment, or knee-sock wholesaler in question. Already featured: 2-for-1 Motel Bar pizzas and Second City tix, $25-off massages, $8-off The Dark Knight IMAX screenings, and $5 Aikido lessons; upcoming frugality will involve sports tickets, five-course dinners from Clandestino's underground supper club, helicopter rides, and Segway tours (to prepare for these, take Aikido lessons)

Today's Groupon: $25-off Steppenwolf tix for Friday's showing of "Kafka on the Shore", a coming-of-age play anchored around trapped-in-time World War II soldiers named Colonel Sanders and Johnnie Walker -- curiously, the two guys you always drag to the aquarium.