This article is a travel topic
American Airlines  is one of the largest airlines in the United States and a founding member of the Oneworld airline alliance. It is the predominant carrier between North America and Latin America and has flights from the US to Western Europe, China, Korea, and Japan. On December 9, 2013 American Airlines and US Airways merged to become the World's Largest Airline.
NOTE: The following list ONLY INCLUDES the hubs and Focus cities owned by American Airlines. This list does not included US Airways. With the merger now completed, all of US Airways Hubs are now owned by American Airlines.
NOTE:The Aircrafts listed are from AA and it does NOT INCLUDE the Pre-Merger US Airways.
American, prior to its reorganization, announced a major fleet renewal. So far it appears to be continuing on schedule, with new 737s coming live, and the new 777-300ER (the present models being -200ER) entering service late in 2012. American is expected to start flying the Airbus A320 and 787 within the next few years as part of this renewal effort, and to finish retiring the MD80.
Frequent flyer program
AA's frequent flyer program is called AAdvantage; it was the first frequent flyer program based on earning miles and the template for most such programs as they exist today.
AAdvantage members earn miles on all Oneworld carriers (although in some cases, only in limited fare codes), as well as, Air Pacific (Fiji), Air Tahiti Nui, Alaska Airlines, El Al, Gulf Air, Gol (Brazil), Hawaiian Airlines, Jet Airways, and select routes on JetBlue. For the current list of Advantage Mileage Earning Airlines refer to here: 
As of late 2010 (with anti-trust approval earlier in the year and the first major changes effective 10/1), beyond the OneWorld membership, American Airlines is part of a new Joint Business Arrangement with British Airways and Iberia, including increased numbers of code-share flights and cooperation on transatlantic flights (including a removal of the prior rule of no mile-earning on transatlantic BA flights.)
A similar agreement for transpacific flights went into effect with Japan Airlines in April 2011, and a (separate) similar agreement went into effect with with Qantas in May 2012.
American has two basic types of its own award tickets: MileSAAver, which is subject to blackout dates and capacity restrictions, and AAnytime, which is not subject to blackout dates or capacity restrictions.
AAnytime tickets generally cost twice as many miles as MileSAAver tickets. Some international markets have "peak" and "off-peak" mile costs for economy class travel which skew this basic formula slightly.
AAdvantage miles can also be redeemed for point-to-point "All Partners" awards to a given destination, which can include a mix of AA and partner flights, including some which are non-Oneworld airlines.
Awards on American flights, as well as some partner flights (as of 8/2012, British Airways, Iberia and Qantas) can been checked and redeemed via the corporate website, while other partners can only be booked via telephone agents.
An informal Wall Street Journal study in 2007 concluded that American was one of the easiest US major airlines on which to redeem miles for free travel.
AAdvantage miles can also be redeemed for car rentals and hotel stays.
AAdvantage elite status is determined by the number of miles or segments you fly on an AA, AA codeshare, Alaska Airlines or mile-earning Oneworld flight. You can also earn status based on your accrued elite qualifying points: you get 1 point per mile traveled on most discounted economy tickets, 1.5 points per mile on full-fare economy and premium class tickets, and 0.5 points per mile on deeply discounted economy tickets. The basic tiers are: 
Elite status members are generally given a "soft landing" if they fail to requalify; Platinum to Gold, etc. Most years, the American Airlines will also offer members with elite status who fell short of the total (but who did at least some flying in the past year; the exact threshold is not publicly announced) a chance to buy status for another year. This generally cannot be repeated two years in a row.
AAdvantage is unique among frequent flyer programs in its challenge program. A passenger can earn Gold or Platinum status by calling AAdvantage, asking to take the challenge, and then racking up a certain number of elite qualifying points (not miles!) within a certain period of time; there is a small fee for enrollment ($240 for Platinum, $120 for Gold, as of August 2012) which is not refunded if the challenge is not completed. The requirements have been stable at 5,000 points in 3 months are presently required for the Gold challenge and 10,000 points for the Platinum challenge. 
It should also be noted that a passenger can only attempt a status challenge when they do not hold that status -- it is intended to bring new people into elite status, not as a method of retaining elite status. So while you can make Platinum with some trans-pacific rounds trips in economy class (or virtually any in business or higher), you will have to follow that up with much more mileage in order to retain your status for more than a year.
AA's main lounge is called the Admirals Club.  Membership costs $500 for the first year and $450 each year thereafter; you can also buy membership with AAdvantage miles, and obtain discounts based on your AAdvantage elite status. There is a discount for a married couple joining/renewing at the same time.
Oneworld Sapphire and Emerald members can use Admirals Clubs when travelling on a Oneworld itinerary that day; AAdvantage Platinum and Executive Platinum members can only take advantage of this when traveling on a same day international itinerary.
American also has a special first class lounge, called the Flagship Lounge, in Chicago, Los Angeles, Miami, London-Heathrow and New York - John F. Kennedy International Airport. Access to the Flagship Lounge is available if you are traveling in first class to/from Europe, Asia, Central America, South America or Mexico City, or if you are traveling in first class on certain coast-to-coast transcontinental flights (in the case of LAX or SFO), or if you are an Executive Platinum/Oneworld Emerald member and otherwise eligible to use the Admirals Club. For first class transcons, you must be booked in F or Z inventory, but this does include AAdvantage awards. For international 3-cabin flights, you must be in First Class, but it doesn't matter how you got there.
London Heathrow also has an Arrivals Lounge open to all arriving first and business class passengers. Economy passengers can also use the lounge by paying US$90 plus VAT at the door. The lounge has showers, drinks, gym equipment and a business center.