A growing trend shows that many Americans are taking on new jobs after their "official" retirement. For the most part, it's because they need the extra cash - but some retirees are simply bored. Whatever the reason, an increasing number of seniors are clocking in and bringing home the bacon for many years after retirement.

According to the U.S. Department of Labor, the number of employed Americans between the ages of 65 and 90 has mushroomed in recent years. As a matter of fact, 6.4% of Americans aged 75 or older (more than one million seniors) were still working in 2006. That was up from 4.7% just 10 years earlier.

So, what exactly are these retirees doing to earn some extra income? Here are eight of the most popular post-retirement jobs. (Retirement might sound like a great idea, but are you really ready to quit your day job this year? Find out in Retire In 2010: What You Need To Know.)

  1. Consultant
    If you were an expert in your field during your working years, why not sell that expertise to other companies after you retire? As countless retirees are realizing that their hard-earned skills and knowledge are highly marketable, many of them are jumping into the consulting business.
    For example, let's say you are the most practiced marketing guru in your company. After you retire, you could offer your marketing services to other businesses - or even your old company. And here's the real kicker: as a part-time consultant, you can charge hourly rates and earn as much or even more than you made when you worked full-time. Plus, as your own boss, you can pick and choose which projects you want to tackle. (Even convicted criminals are becoming consultants with Wall Street prison consulting. Check out Former Convict? Become A Consultant.)
  2. Caterer
    After inhaling your scrumptious homemade lasagna and savoring your mouthwatering caramel apple pie, do family and friends often say things like, "This is delicious…you could sell this!" If so, catering may be the ideal post-retirement career path for you.
    Many retirees who are whizzes in the kitchen are starting their own catering businesses. It gives them the opportunity to turn their favorite pastime into a profitable business venture. (Many are choosing to work longer in order to rebuild their nest eggs, but despite the extra income, there are drawbacks. Learn what they are in Working Longer: Will It Hurt Your Retirement?) Let's say your six-year-old granddaughter has more business smarts in her little finger than you do in your entire body. No problem. You don't have to start your own catering business to earn some extra dough. You can always offer your valuable services to other local catering companies. That way, you can cook and bake until your heart's content without having to deal with the accounting and marketing headaches a business owner must face.
  1. Store Greeter
    You're probably rolling your eyes and thinking, "The retired store greeter? How cliché!" Although it may seem a little stereotypical, these welcome wagon positions are still extremely popular with retirees. Not only is greeting a low-stress way to earn some extra income, but it's also the perfect prescription for bored retirees who want to get out and socialize.
    Plus, store-greeter positions aren't just limited to big box stores and supermarkets anymore. These days, businesses from car dealerships to electronics stores are hiring happy greeters to welcome customers. A Texas-based chain of hardware stores offered George W. Bush a post-presidential greeter position at their Dallas location. In a letter to the former president, the store owner pointed out that this job would be "much less stressful" than his previous job.
  2. Floral Assistant
    Scores of green thumbed seniors are taking on post-retirement jobs at their local florist's shop. These floral positions are popular with flower-loving retirees because they offer flexible schedules and typically require little experience.
    So if you have a passion for plants, floral assistant may be the ultimate post-retirement position for you. (These habits could have you working longer, retiring later and finding yourself flat broke in your golden years. Find out 6 Things You're Doing To Delay Your Retirement.)
  1. Temp
    An increasing number of unemployed Americans, including loads of retirees, are signing on with temp agencies. As the name suggests, temp agencies provide temporary positions that can pay anywhere between $10 and $30 an hour.
    Temp agencies help a wide range of companies find workers to temporarily supplement their staff, fill in for employees who are on vacation or maternity leave or help out with special, short-term projects. Statistics show that about 30% of temp jobs lead to full-time positions. And there are plenty of temp jobs to go around. One of the largest employers in the world is Manpower Inc., a Milwaukee-based temp agency.
  2. Tour Guide
    You're older and wiser than all those spring chickens out there - and you saw some of the most interesting historical events unfold during your lifetime. So, why not become a tour guide?
    Many history buffs settle into post-retirement positions as a guide at the local museum, historical monument or sight-seeing tour. These part-time tour guide positions give seniors an opportunity to share their knowledge and socialize with interesting tourists from around the world.
  1. Retail Worker
    Whether it's with Home Depot or Target, retail positions are skyrocketing in popularity with seniors. Other than the typical store greeter, retail jobs include cashiers, stock room associates, floor supervisors or retail management positions. Retirees are drawn to these retail jobs because they generally offer a flexible schedule, plenty of social interaction and decent pay.
  2. More of the Same
    Of course, in these tough economic times, many retirees are simply staying put in the same job they've held for years. Once they reach their official retirement age, some seniors ask their employers if they can work fewer hours and take on a smaller workload for a reduced salary. For many retirees, this option gives them the best of both worlds: they get to keep the job (and income) they know and love while gaining some extra time to take on new hobbies, travel and relax at home. (If your goal is to enjoy every cent you've worked so hard to save, here are some tips on how to spend it all without running out. Don't miss The Spend-Every-Penny Retirement Plan.)

    The Sky's the Limit

    Obviously, we've just scratched the surface with these eight post-retirement career options. From childcare work to customer service positions and everything in between, there are countless jobs available for retirees whether they're flat broke or just plain old bored.

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