How Much Is A Stamp?

With e-mail replacing letters and the web providing an easy way to pay bills, I’ve found no need to buy stamps. So when the rare occasion arrives when I need to mail something off with a stamp, I’m clueless as to what they actually cost. Thankfully there is, which like the name says, tells you how much a US postage stamp costs. Stamps cost 42 cents now!?!? When did that happen?