Oh it is that time of the year when flu comes around like a bad house guest, and according to CDC officials there should be enough to go around to those who want it.
The CDC has a page entirely devoted to the flu. The page includes information for patients as well as health professionals.

For patients
What You Should Know About the Flu:
Includes: Key facts, Prevention and vaccination, Questions and answers, What to do if you get sick, Flu activity, and Information for specific groups.

For healthcare providers
Information for Health Professionals:
Includes: Vaccintation, Infection Control, Antivirals, Diagnosis, Surveillance, Patient & Provider Education, Training, Background, Bulletins, References & Resources

You might want to bookmark http://www.cdc.gov/flu/about/qa/flushot.htm which lists who should get a flu shot.
According to the CDC people who should get vaccinated each year are:

People at high risk for complications from the flu, including:

• Children aged 6–59 months,
• Pregnant women,
• People 50 years of age and older, and
• People of any age with certain chronic medical conditions;
• People who live in nursing homes and other long term care facilities.

People who live with or care for those at high risk for complications from flu, including:

• Household contacts of persons at high risk for complications from the flu (see above)
• Household contacts and out of home caregivers of children less than 6 months of age (these children are too young to be vaccinated)
• Healthcare workers.

Some people are fortunate to have employers who have people come in to give flu shots to employees. But for those who do not have that perk and their doctor's office doesn't have them, you can find flu clinics in your area at http://flucliniclocator.org/. Other options are to call your local or state health department. Children vaccinations are different than adults, so it is important to call ahead and specify interest in children's vaccinations.