Comment Tragic, but not catastrophic (Score 5, Interesting) 79
I once joined a project where one of the core developers had mysteriously disappeared. He had been one of the early designers, and was the only person who actually knew how his areas worked.
It took a small team about a year to fully understand all of his work, but the project survived. To this day, four years after his disappearance (three after his body was pulled from a river), we still find some code with his name on it, and it's a tradition to assign it to the newest team member to read, understand and deliver a report on how it works. It's a rough process, but we got through it eventually.
His legacy on the project is as an object lesson in the necessity of good commenting, and a reminder to management that they must be wary of one-man teams.