NEW YORK (CNNMoney.com) – Forty-plus hours a week for 49-plus weeks a year for 40-plus years is - you've got to admit - a lot of time to spend at your desk, even if you love your career.

So it's no surprise when, looking up from your Blackberry, you find yourself imagining all the things you could be doing with your time besides committing the majority of your prime years to the job.

You might, for instance, fantasize about spending a month or three:

• Traipsing through Australia
• Working with your favorite charity
• Spending long stretches of unhurried time with your kids
• Teaching a class
• Learning to surf
• Training for a triathlon
• Helping to rescue wild horses
• Building a deck
• Doing whatever strikes you when you wake up (aka nothing)

Now imagine your company lets you, and tells you your job will be waiting for you when you come back.

For a small minority in the corporate world, that's not just a wistful, pie-in-the-sky dream.

Roughly 11 percent of large companies offer paid sabbaticals to employees and another 29 percent offer unpaid sabbaticals, according to the latest data from the Society for Human Resource Management (SHRM).

Even though paid sabbaticals are typically the province of large companies, 16 percent of small companies and 21 percent of mid-size companies today do offer unpaid sabbaticals.

Five years ago, only 15 percent of all companies offered unpaid sabbaticals.

Call it enlightened or call it shrewd. But employers that offer sabbaticals know that making it easy for employees to explore their interests beyond their career is a good way to build loyalty, increase retention and foster greater creativity at work.

"The theory behind sabbaticals is that everyone wishes to do something perhaps radically different for some period of time," said J. Robert Carr, SHRM's chief professional development officer.

A sabbatical can curb the impulse to quit. "You don't want talented people to walk out the door. The goal is to hold on to your employees," Carr said.

Sabbaticals typically are offered to employees who have received solid performance reviews and have been at a company for seven to 10 years.

And beyond insisting that employees not work for another company – in particular, a competitor – some companies may require employees to work for a charity or social service organization during their leave.

But some place no restrictions whatsoever on what you do. Teach, nap, garden, pet ponies ... your call.

If you're wondering just what kind of sabbaticals are on offer, here's a look at what six companies provide:

After 7 years working at investment firm American Century, you're allowed to take a four-week paid sabbatical on top of any vacation you may have. Then five years later you can do it again. What you do with that paid month is up to you.

You have to apply for the sabbatical, giving at least 90 days' notice. And you need to work with your manager to develop a plan for how your work will be handled in your absence.

Since 1991, employees who have been at American Express for 10 years can apply for a paid sabbatical lasting between one and six months.

The company asks that employees on leave work for a nonprofit or school of their choice. The only restriction: they may not work for groups with political or religious affiliations.

Since 1986, partners at this law firm are entitled to a paid sabbatical, the length of which depends on their age and tenure. A partner between the ages of 30 and 40 may take one month off if he has been a partner for five years or has been with the firm at least 10 years, of which three have been as partner.

Partners between ages 40 and 50 get two months; those from 50 to 60 get three months and those from 60 to 70 get four months paid leave.

The point of the leave is revitalization, so no restrictions are placed on a partner's activities.

In 2004, the investment bank launched The Public Service Program.

PSP allows its top managing directors and vice presidents/executive directors a year of paid leave to pursue work with a charitable, public service or cultural organization of their choosing.

Only those who have been in their jobs at least 12 months and with the investment bank at least four years are entitled to apply and from that pool a select group is awarded the leave.

At this Seattle-based law firm, lawyers with 7 years of tenure, salaried staff with 10 years and non-exempt, hourly staff with 13 years may apply for two months of paid leave to spend any way they wish.

The only two requirements: they can't work for another company and they have to let the firm know what they're planning to do and why those activities are meaningful and rejuvenating to them.

Some of PwC's business units have had a sabbatical program for years, but this year the company is rolling out a pilot program for its Advisory practice that it will launch firm-wide if it proves successful.

Two types of sabbaticals will be offered: one for personal growth and development and one for social services.

Both range from a three-month minimum to a six-month maximum. In exchange, employees have to agree to stay with PwC for at least a year after their return.

During the sabbatical you'd be paid between 20 percent and 40 percent of your salary with most benefits maintained.

You can apply for a sabbatical as early as your second year at the firm.

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See other companies offering sabbaticals who have made it onto the list Fortune's 100 Best Companies to Work For.

Jeanne Sahadi writes about personal finance for CNNMoney.com. For comments on this column or suggestions for future ones, please e-mail her at everydaymoney@cnnmoney.com.