Here's a blog I put together that covers 17 of the world's top companies and examples of how they engage their employees: http://www.fieldboom.com/blog/employee-engagement-activities/.

Examples include how Zappos has built such a high level of engagement. Zappos created several ways to engage its employees, including Zappos Zollars. Employees can earn the company currency by going above and beyond in their work and the Zollars can be used for branded goodies, charitable donations or in raffles for bigger prizes.

Their employees can also participate in their Grant-a-Wish program, which allows them to suggest and grant wishes for their team members. It’s a great way for employees to express gratitude to other people in the company and give them a fun experience – whether that’s dance lessons, riding in a hot air balloon or taking a mini vacation.

The company’s emphasis on engagement starts from the moment someone is hired. After their initial training, they participate in a scavenger hunt that helps them get to know other employees.

For example, they may be tasked with finding someone wearing a Zappos hat and asking them about their job, so they can get to know them. Simple but mighty effective.