Call it an all-you-can-eat perk.

In an effort to foster employee creativity, curb turnover and prevent burnout, some companies are offering their workers the ultimate benefit: unlimited paid vacation.

By showing that they trust their workers, these employers say, they are cultivating a culture of even deeper trust. Though the practice is still experimental, these companies say they've seen little abuse of the system so far.

Red Frog Events, a Chicago-based weekend entertainment organizer, hasn't tracked employee vacation time since bringing its first hires on board about two years ago. Many of the company's roughly 80 full-time workers "take a couple of days here and there" to recharge or fulfill personal obligations, like attending a friend's wedding, but no one has abused the company's unlimited-vacation-time policy, says human-resources director Stephanie Schroeder.

Unlimited vacation is offered most commonly at smaller companies, where schedules are easier to coordinate, but it is still a relatively rare benefit, experts say. Just 1% of employers currently offer the perk, according to the Society for Human Resource Management's 2012 Employee Benefits Survey, which polled 550 HR professionals. Most companies offer a fixed vacation program: The median full-time U.S. worker received 2.6 weeks of vacation last year, according to an analysis of 465,000 workers by PayScale, a firm that collects compensation data.