Virtually every consultant at McKinsey & Company thinks about quitting. In fact, most of the company's new recruits have thought about life after McKinsey before they've actually begun working at the firm. And it's not that everyone wants to leave, far from it, it's just that the firm has done an amazing job making sure former colleagues have as vibrant a career as they would if that stayed.

When visiting business school campuses, recruiters for the firm will talk openly about the extensive impact of being McKinsey alumni. "We will talk about not just the great training you'll get and the great problems you'll work on and the wonderful clients you'll work with, but also the fact that the firm does celebrate those lifelong connections and how we keep our alumni connected," said Sean Brown, the global director of alumni relations at McKinsey & Company. And why wouldn't they? Alumni from the firm have gone on to become CEOs of global companies, start entrepreneurial ventures, or transition into the nonprofit or government sector. And much of that is due to the support McKinsey provides post-departure.

And it works. While talking about life after McKinsey isn't the only reason it draws top talent, it's certainly a big factor in the decision new recruits make to sign on.

McKinsey isn't the only firm to boast about its alumni network. LinkedIn, Microsoft, Proctor & Gamble, Chevron, and a growing number of major companies are all learning the importance of taking care of employees after they leave and the return on investment it makes in the form of new talent. One company, another consulting firm, goes even further.

The consulting firm Accenture boasts more than 100,000 alumni in the United States alone. These alumni stay connected to their old company through its online member portal and receive access to both a directory for alumni and a second directory of businesses started by alumni. The Accenture alumni network also encourages outside firms to post openings for which they're looking to hire former Accenture talent. The company helps their former employees find new jobs.

Perhaps most intriguing, the goal of soliciting these openings isn't just to find former Accenture people jobs at new firms, but also to help find the newest sources of talent for Accenture. The company actually offers Accenture alumni referral bonuses for suggesting candidates for Accenture job openings or even for general referrals for which there is a company fit. The rewards are competitive with many companies employee referral bonuses, ranging from $2,000 to over $7,000. Almost one-third of new hires at Accenture are candidates who were referred -- and a significant portion of them were referred by former, not current, employees.

The reasons make perfect sense. All employees know best what the job demands and qualifications are, as well as who would be a good fit to join a company. But only former employees are working in a place where they see a near-constant stream of potential new recruits (since current employees spend most of their time around other current employees).

Between taking care of employee alumni and incentivizing them to refer new potential hires, it turns out that being a great place to work may hinge on being a great place to have worked.