I've worked with a few companies where a significant portion of the staff have been there a long time--the sort of place where you join after high school and stay until retirement and the "new guy" has been there over a decade.

One CEO told me their secret to employee retention:

1. Compensate people a little better than you need to

2. Promote internally

3. Be one of the few employers in town so that 1 and 2 compound