Usually, we're not so big on buying miles. But what if your airline gives you a 100% bonus? 

That's what's happening on US Airways. Through September 15, buy 50,000 miles for $1375 and you get an additional 50,000. You only need 90,000 miles to fly to Asia round-trip from the US in business class, for example, on airlines in the US Airways-affiliated Star Alliance (such as Singapore, Asiana, and Lufthansa; see US Air's partner award chart [pdf]). Needless to say, you'll also have to pay taxes on the "free" ticket, which could set you back another $100-500 or so, depending on your destination. And you might have trouble finding the exact dates you prefer, since free seats are capacity controlled. But you still come out on top, saving quite a bit on travel in business class.

You needn't buy 50,000 miles. The minimum purchase is $1000 miles, for $27.50. Note that your Dividend Miles account must be at least 12 days old to qualify. The offer also extends to gifting miles.