Lifehacker’s Kevin Purdy just posted this article:
Windows/Mac/Linux (Firefox): Flight-tracking website Yapta, previously mentioned here when it was an Internet Explorer-only extension, has released a Firefox version of its tagging tool. The same principle applies—head to an airline or travel aggregation website, start the standard date/passengers form rolling, and then click the “Tag it with Yapta” button on any flights you want to watch. You can then set Yapta to email you any time your tagged flights change in price by a dollar amount you choose. Yapta is a free download, which requires a sign-up at Yapta’s website to function, and it works wherever Firefox does.
Read the rest at Lifehacker