Often there is this concept bandied around that failure breeds success. Sometimes you'll hear, "fail fast," or "fail forward," and so on, but basically the premise is to fail, learn from the failure and move forward.

"A startup's best friend? Failure" from Business 2.0 goes over a few cases of entrepreneurs failing and the results of those failures.

It is interesting, because in a way it glamorises failure, which as I'm sure most of us know, is just no fun. I suppose to me it is more about a certain philosophy, possible more an like agile, or extreme business planning, rather than about failure. One of the things about the examples is that each person used their failures (which they thought would be great successes) to learn and adapt - maybe that is the real issue here, do we make the same mistakes?

One thing I did find particularly disturbing in the article,

"Failure is the enemy of efficiency, but it's the best way to learn," says Robert E. Gunther, a business consultant for Decision Strategies International in Conshohocken, Pa. Gunther encourages clients to make "deliberate mistakes" to learn faster.
How can you make a "deliberate mistake" AND learn from it? It doesn't make sense. To make a "deliberate mistake" you have to already know what the mistake is - hence no learning opportunity.

So which were your most "useful" failures, and how did that impact your life going forward from there?