Somehow I missed this announcement altogether: The post office is expected to up first-class postage to 42 cents in May but also introduce a new stamp that might take some of the sting out of the price hike: The "forever" stamp, which can be purchased at the price of a current first-class stamp and used as first-class postage forever, no matter how often rates are raised.

Hard to believe it's been barely a year (January 2006) since the last postage price hike, eh?

Anyway, this whole "forever" stamp business adds a new wrinkle in buying postage. Depending on what happens to inflation, postage prices could begin to increase more rapidly and more steeply. Does it make sense to stock up on 39 cent stamps today for that day when it costs a dollar to mail your cable bill?

Well, the Poindexters at The Simple Dollar ran the numbers to figure out how many "forever" stamps are worth buying and when. The answer: Buy about one year's worth just before rates go up. Don't buy more than that, as you'll be wasting money you would otherwise be able to invest for a better return. Read the full story at the link above for graphs and some math.

Of course, there's an even better way to save money on postage: Pay your bills online. You might be surprised how sophisticated your bank's online bill-paying services have become, and in many cases, they're completely free to customers with a checking account.