The year's top travel sites: Check out the 2009 Luckie Fifty

We live in a time when Americans simply can't afford to risk a bad vacation

Far fewer Americans are planning leisure trips this summer than in years past. And those who are vacationing are being tremendously careful to plan and budget their journeys more doggedly than ever before.

To help travelers and marketers alike keep tabs on the most effective tools out there, I'm excited to introduce the 2009 Luckie Fifty. This is the second year my colleague David Stutts, Luckie & Company's director of brand planning, has compiled a list of the most useful, innovative and fun travel sites on the Web.

Click here to download the full PDF of The Luckie Fifty.

And don't miss this handy one-sheeter, which you can print out and pin on your office wall next to that picture of a Saint Martin cabana.

There's just a ton of great stuff in the report, so I won't inundate you with all of it here. But after the jump, you'll find David Stutts' summary of 10  social networks that are redefining how travelers connect and share.