Europe has its own versions of JetBlue and Southwest, and these discount airlines can save you money when you want to hop around the Continent. The website EuroCheapo, best known for its guides to budget hotels and inns, has just launched a guide to budget airlines in Europe: eurocheapo.com/flight. On the left of this page, you'll find a column with a list of the 43 discount airlines in western and central Europe, from the ones you already know (easyJet, Ryanair) to the ones you've never heard of (Helvetic, for instance). Click on an airline name to read the review.
Each review hits the pros and cons and runs down the routes that the airline offers. I particularly like how the site invites reader feedback on each airline's carry-on luggage policies. This is a weighty issue for Americans because U.S. airlines have more generous weight limits for carry on items than most European low-cost airlines.
Of course, there's a fare search engine, too, powered by Wegolo.com. Like all search engines, it's not perfect, but at least this one allows you to compare the fares it fetches on the same screen with fares from major booking agencies such as Orbitz, Kayak, and so forth.
I wish EuroCheapo made it easier to find their listing of routes by country. For example, if you to eurocheapo.com/flights/countries, you can scroll to the bottom of the page to see a box "find flights within Europe by departure country." You can click on a country (say, Ireland) and see a map of its major airports, all budget flights from Ireland (by arrival city and by arrival country). If you're like me, seeing the routes on a map is a faster, more intuitive way to figure out if one of Europe's low budget airlines could be of use to me as a traveler.
Overall, kudos to EuroCheapo.