Whilst collaboration is typically seen as something that occurs between you and your employees, that really is just the tip of the iceberg.  Open innovation, or crowdsourcing, have offered a potent example of how companies can successfully engage with external stakeholders, whilst the story last month that Brian Acton of WhatsApp fame had been turned down for a job by Facebook years before they shelled out $19bn on his company highlight how important it is to keep tabs on those you reject during the recruitment process.

Former employees, and of course the never were employees, should all form part of corporate alumni networks that form a substantial chunk of your external collaboration efforts.  I wrote last year about the YourEncore social network that was built by Proctor & Gamble and Eli Lilly to ensure the knowledge of retired employees wasn’t lost.

Such neworks are increasingly commonplace.  Microsoft have developed their own network for alumni, whilst Conenza is a commercial service designed to help companies build such networks of their own.

It’s a practice that the consulting companies have long since adopted.  McKinsey for instance have a database of over 25,000 former employees.  Those alumni have access to a dedicated website showing them the latest news and analysis from the company.

Other consultancies have done a similar thing, effectively treating former employees as excellent routes into the companies they leave for.  The Boston Consulting Group ensures that leavers exit the company on good terms, helping them negotiate their new contract for instance.  Those alumni then are part of their external network of contacts, helping the company secure both work and new talent themselves.

Of course, this relationship doesn’t always have a beneficial impact.  General Electric suffered a blow to their reputation as the best place in the world for developing managers when several high profile alumni flopped whilst leading other firms.

With the cost involved in running a successful alumni network plummeting due to enterprise social networking tools, it should nevertheless be a no brainer to ensure that your alumni have a reason to stay in touch with you.