I've been using the private beta of Farecast for a couple months now and I've really enjoyed it. With the launch of their public beta release today, everyone (in Seattle & Boston at least) can take advantage of the high quality data mining and spiffy GUI that the Farecast team has put together.

The screenshot above shows me the best times to buy tickets from Seattle to LAX to get the lowest fares. My best fare will be available if I buy a ticket that leaves on September 6 and arrives the 12th. They've also got the ability to tell you when you should buy the ticket - today, tomorrow or in 30 days, based on how ticket prices have historically fluctuated and how the airlines price fares.

What has Farecast done right:

• Easy to use
• Useful, high quality information
• Simple, attractive GUI
• Spiffy AJAX functionality (at least in Firefox - IE was giving me trouble with those graphs)
• Strong Information Scent - I know exactly what I can do, where to go and how to interpret the data.

What they have ahead of them:

• The challenge of making a dynamic portal into a site that get attract search traffic
• Marketing the site beyond the web - public relations, mentions in the press, etc.
• Expanding quickly to other markets before a competitor jumps into the space
• Forming partnerships and revenue streams without sacrificing the user experience

If you're aching to try Farecast, vote for your city here. Any suggestions for the Farecast team? Just leave them below - I have inside information that they're SEOmoz regulars :)