Last second award availability is routinely fantastic on United flights and on certain Star Alliance partner flights. Use your United miles (or any other Star Alliance miles) to book a last minute trip right now to anywhere in the world for Christmas or New Year's!
Australia
You could be in Sydney Harbour for the fireworks. United flies daily from Los Angeles and San Francisco. Both routes have Saver award space this week in economy, business, and first classes for two passengers.

In Part 1, I shared my experiences at the 2012 Euro Cup and how they informed my plan for the World Cup. I also discussed the flight and hotel awards I booked for myself.

I just booked myself a roundtrip First Class award from Honolulu to Sao Paulo, Brazil during the 2014 FIFA World Cup. I also booked myself five nights at a hotel in Sao Paulo.

Rooting for the Home Team (Poland) at the 2012 UEFA Euro Cup!

The cost?

125,000 US Airways miles
100,000 IHG Rewards points
$109

If you want to go see the biggest sporting event in the world in the world's best footballing (soccer) country, this is a once-in-a-lifetime opportunity.

Update at 5:49 PM ET on 12/20/13: Many commenters are saying they've had problems with aa.com showing "phantom award space" on airberlin flights. I have never had that experience, so I was surprised by the reports, but I'm sure they're accurate. My advice changes in light of this info.

Did you miss 20k Miles (or Less) to All of South America All Year yesterday? That post is a competing trick with this one, and it might be an even better deal for you.

Chicago to Santiago "should" cost 30,000 American Airlines miles each way in economy.

Or: Save 10k Miles by Adding a Free Oneway

Summer airfare--during our summer or theirs--to Southern South America usually tops $1,000 per person in economy.

But you can get to South America this summer for only 20k American Airlines miles one way.

All the legacy carriers--Delta, United, American, and US Airways--charge 60k miles roundtrip on Saver economy awards to Southern South America, which includes Brazil, Argentina, Chile, Bolivia, and Paraguay.

American and United let you go one way for half the price while US Airways and Delta charge 60k miles for one ways.

American is even more generous with

Per this thread on Flyertalk, United.com no longer displays Singapore Airlines award space. This abrupt announcement might seem like terrible news to award bookers, but it's more of an inconvenience than anything else.

United.com is the easiest way to search for Star Alliance award space. It's far from a perfect booking tool, however.

Update 12/17/13: The 50k mile offer on the Lufthansa card is dead.

United, Lufthansa, US Airways, Air Canada, ANA, Singapore, and TACA/Avianca are all members of the Star Alliance.

With few exceptions, all of their miles can be used with equal access to any Star Alliance carrier's Saver award space.

You cannot transfer one type of miles to another. For instance, you cannot transfer your Lufthansa miles to your United account.

But you can combine the power of your miles by using miles from several different accounts to book awards on the same flight.

Our Award Booking Service has been rocking and rolling lately. Busy frequent flyers love the personal attention we give each itinerary, as well as our expert knowledge of award programs.

The MileValue crew has a battle-tested recipe for award booking success.