Annual FM3 and FM2 renewal:

Renewals can only be made within México at your local INM office and must be made within 30 days before your FM3/2 expires. Renewals can not be made from any Mexican Consulate in the USA

INM has a webpage where you must create a personal account that will begin the process. This is not optional, you must apply online. If you are married or have children, each person must make their own application. Each application is registered with the INM and given a specific file number.
This is the link to the INM Application Form  ( Formato migratorio para trámites de estancia )
*A sample of the Application Form with English translation is available below

After you save and print your application, take it and the file number (pieza) to the local INM office where they will tell you if anything more is required. They will send you to the bank to pay the fee.
You will need to take your FM3 or FM2, the original and a copy of the picture and personal data pages of your passport. Also required are color photos, 2 front and 2 right side (infantile size) with no jewelry. (Map to Photographer)

In most, but not all offices, you no longer need to take bank statements or proof of address. Instead you must write a letter in Spanish stating that nothing has changed in your income or residence. A suggested *sample of this letter is available below

Checking on the progress of your renewal can done from this website. The file number( Pieza) is your application ID number. The INM office will give you the Contraseña (password) and the NUT numbers when they accept your papers. After you enter the Pieza and Contraseña, click on Buscar, and a new page will come up asking you to select the NUT - probably only one choice.  Then all the particulars of your application will appear on monitor screen.

Leaving the country while an application is pending: The new renewal procedure is much faster than the old one, but there still could be a situation requiring you to leave the country while your renewal is in the hands of the INM.  There is a procedure to take care of that. It's called Permiso de Salida y Regreso. You can apply at the INM office where they will sell you a permit that you can use to exit and re-enter the country. 

Mexico recently began issuing a NEW 180-day Forma Migratoria Multiple called the FMM.
Because recreational boaters are normally in Mexico for tourism purposes, not business purposes, this FMM is the form that they should use. 

Like the previous tourist card, the NEW FMM is also good for 180 days, beginning with your arrival in Mexico. The difference is that with the old card the tourist had to leave Mexico before the 180 days expired and get a new one upon re-entry.

The NEW FMM is available free at all ports of entry. A passport that is valid for at least another 6 months is all that is needed to get the NEW FMM re-stamped at any immigration office before the 180 days expire. Boaters who are currently in Mexico with the old card can also get it replaced with the new one at any immigration office.

How do I obtain a tourist card (FMM)?
Working hand-in-hand with Mexico’s innovative Temporary Import Permit (TIP), the new law allows boaters to keep their boats in Mexico for up to 10 consecutive years, and they can be berthed in a marina while they depart the country.

For the most part, tourists who drive across obtain their tourist card from an immigration office at a border crossing point. They are also available at border zone airports, airlines flying to Mexico, travel agencies and other ports.Tourist cards are no longer available at Mexican Consulates. Keep in mind that if you obtain your tourist card before crossing the border, you will still have to stop at the Mexican immigration office at the border to document your entry date and to have your tourist card stamped by immigration officials.

Before the tourist card is fully issued, you will be sent to the bank next door to pay for it and come back with the receipt to show the immigration official. The immigration office in Tijuana and the bank are open 24 hours a day 7 days a week.

How much does a tourist card (FMM) cost?
As of February 2011, tourist cards cost $262.00 pesos (just over US $21) and can be issued for up to 180 days. It is advisable to have your card valid for 180 days even if you don't plan on staying in Mexico that long. It is easier to already have the time granted to you than extend your card later if you stay longer.

Traveling with Minors
If a minor (person under 18 years old) is traveling with only one parent or another person it is necessary to bring a notarized letter signed by the absent parent(s) stating that the minor is permitted to travel with whomever they are traveling. If the parents are divorced, proof of sole and physical custody must be presented. If one parent is deceased, a death certificate is required. NOTE: Tourist cards are issued per person including minors and infants.

Tourist Card Tips
Make sure that the Mexican officials stamp your card.
Keep your card in a safe place. It is better not to keep it on your person.
Write your tourist card number down and keep it separate from your actual card. If you lose your card, this will help to expedite the situation with immigration.
If you do lose your card, you will need to go to a local immigration office to obtain a new one.

July 2011 - New Tourist Card for Mexico