Brooke Folk, 68, was well into retirement, and looking for both a hobby and a path to some extra income.

He found both as a freelance writer for Fiverr, an online freelancer services site that pairs writers, musicians, business consultants, and other freelancers with paying clients. He started by selling custom short stories on the site for $5 a piece.

“That may not seem like a lot, but like any new business venture, there’s an investment of time and resources to get things off the ground,” Folk explains. “Now I’m a top-rated seller on the platform and earn about $10,000 a year selling my short stories, including longer stories that sell for $1,000 and more.”

Folk is hardly the only retiree looking for an additional income stream in retirement.

Take Kurt O'Neill, a freelancer with the on-demand tax-filing app Taxfyle.

“I’ve always had a knack for numbers, even as a young kid,” says O’Neill. “Perhaps unsurprisingly, I became a certified public accountant and have worked for traditional accounting firms for more than 20 years, serving as a CFO as well.”

O’Neill says he’s been passionate about delivering his clients a quality, no-stress service at a competitive price.

“So when I heard that Taxfyle was launching an on-demand tax filing app, it piqued my interest. I had never considered working in the gig economy, but signing up with Taxfyle was quick and painless.”

Once he shared his credentials electronically, O’Neill immediately began looking for clients.

“Things were a little slow at first, but have undoubtedly picked up with time,” he explains. “Now, I’m able to expand my practice and help people file their taxes from the comfort of my own home, even in my pajamas, with no need to drop off documents or travel to meet with clients. There’s less legwork for both accountants and users, and the tax filing services are actually more affordable for users than using a traditional firm.”

“I take pride in helping my clients get the most from their tax returns, and I don’t think that will change with age,” O’Neill says.

With 22% of Americans already participating in the so-called sharing economy, and 90 million Americans paying for sharing economy services like Uber, Airbnb, and other freelance services, there is plenty of room for a part-time sharing economy gig in retirement.

Become a tasker on a tasking platform.

Like Folk, you could offer up your skills on tasking platforms like TaskRabbit, Fiverr, Amazon Mechanical Turk, and Upwork.

Folk says starting a part-time business like this later in life may seem daunting to some retirees, but freelancing has helped him generate income to supplement his Social Security benefits without putting his savings at risk.

“Best of all, I’m able to work on my own terms,” he says. “As a former small business owner, it was important for me to be my own boss in retirement…It’s ultimately up to me if I want to work 30 hours in a week or five. My writing also allows me to explore a passion that I never thought I’d be able to pursue, let alone monetize.”

You’ll need to sign up for these sites and target specific “talent” areas to increase the odds of finding work.

Currently, freelance writing, translation, digital graphics, software, mobile app development, and Uber-like transportation skills are highest in demand.

Pay varies on these sites, from $5 to $100 or more per task, depending on client demand and your experience in getting the task or project completed on time.

Drive with a ride-sharing service.

Uber has changed the transportation game plan, and now there are a variety of ride-sharing services that anyone in retirement can drive for, including Lyft and Turo.

“This is a convenient way to earn some extra cash in retirement,” says Glenn Carter, founder and blogger at the Casual Capitalist, a sharing economy blog. “It works because retirees have more time on their hands and already have the vehicles they can use to ferry people around. An added advantage is that they can work when they feel like it, unlike with being in employment where there are set hours.”

To get started with Uber or Lyft, you must complete the driver application on or on; get your car inspected by Uber or Lyft for no cost; and pass a background check (both companies look for DUI offenses, a criminal record, and/or a history of reckless driving.)

Rent out spaces in your home.

Many people in retirement have their own homes. Retirees can take advantage of that situation and rent out a room or their entire house through sites like Airbnb, VRBO, and HomeAway and make some extra cash. The advantage here is that it doesn't require much time, and they utilize resources that would otherwise go unused.

Walk and host pets.

Pet services like Rover and DogVacay are another area that someone in retirement can cash in on, says Carter. “Apart from having a good time, retirees also get the company of pets and earn some money providing a crucial service for busy professionals that need their pets taken care of while they work.”

Whether it’s dog walking, car driving, or freelance writing, there are plenty of nontraditional ways for retirees to earn some extra cash — and many are doing it.

MagnifyMoney is a price comparison and financial education website, founded by former bankers who use their knowledge of how the system works to help you save money.