Currently only [http://www.travelgrove.com/ Travelgrove's meta search engine] is showing the miles that can be earned for each flight. In cooperation with MileBlaster, extras like credit card bonuses, hotel bonuses, special offers are also available, and the results can be ordered by the percentage of the free flight that can be gained by booking the given flight, so it is definitely a good choice for frequent flyers looking to collect enough miles for a free flight.
Your airline of choice may be a member of an '''airline alliance''', which allows you to earn and use your miles on other airlines in the same alliance as well. The big three alliances are [http://www.staralliance.com Star Alliance], [http://www.oneworld.com oneworld] and [http://www.skyteam.com SkyTeam]. With the many frequent flyer programmes out there, it's simpler to be a member of one programme per alliance, at most.
In case of a merger between carriers, the following scenarios usually apply: *if you have frequent flyer accounts with both parties to the merger, the miles in both accounts will be consolidated into the frequent flyer programme of the new/surviving carrier; a representative should be able to contact you with regards to the ins and outs of the new account *if you have a frequent flyer account only with the acquired party to the merger, a new account will be created and all the existing miles in your previous frequent flyer account will be transferred there; a representative should be able to contact you with regards to the ins and outs of the new account *if you have a frequent flyer account only with the surviving party to the merger, your frequent flyer miles should remain unaffected *if you accrued miles from flights with both carriers but had the miles credited to the frequent flyer programmes of their partners not involved in the merger, your miles with the latter should remain unaffected
Being on a frequent flyer programme of a particular carrier makes it more convenient to make bookings with that carrier. When you log-on using your frequent flyer number and book a flight, your details (such as name, passport details etc.) are automatically filled-in whether the flight is mileage accruable or not.
You may also be able to claim points from '''other sources'''. Credit cards affiliated to a program are particularly useful, as you'll typically get miles every time you use the card and this can quickly rack up to a free trip per year, but hotel stays, car rentals and even mobile phone bills may also garner you points.