When I was growing up, my dad used to take me fishing. Sometimes we'd fish with a line, usually for cod or snapper. As is the way with fishing, we'd often catch other, less-desirable fish and have to throw them back. But some of them, even though we didn't consider edible for us, were good enough for other fish, so we'd chop them up and use them for bait. They were a useful by-product.

Other times we'd fish with a net—either actively trawling or leaving the net in a channel overnight. Just like with line fishing, we didn't want a lot of the fish we caught. Starfish, I recall, we're a real pain to untangle from the net, but not as bad as the crabs—they had sharp, snappy bits. It took ages to untangle them and then, for all our effort, we had to chuck them back.

One day, long after I'd left home for university, mum and dad discovered that cooked crabs taste delicious. They discovered this when some of the local fishermen started selling cooked crabs near the local wharf. It seems strange, considering that we lived in a fishing community, that no one had ever cooked crabs before and that they generally were considered a waste. It wasn't until the more valuable fish stock started to shrink that commercial fishermen started looking elsewhere. It turns out that the crabs are not only delicious but also a profitable by-product.

According to Wikipedia, a "by-product" is a secondary or incidental product deriving from a manufacturing process, a chemical reaction, or a biochemical pathway and is not the primary product or service being produced. A by-product can be useful and marketable, or it can be considered waste. Jason and David from 37signals have a blog entry about sell your by-products. They turned that blog entry and dozens of others into their book Rework, a delightfully short and provocative book. The book is a by-product of their blog (and where I "borrowed" this idea from). Ruby on Rails is another by-product of their work at 37signals, where they sell a few popular and profitable products.

One example they give in their book is that Henry Ford learned of a process for turning wood scraps from the production of Model Ts into charcoal briquettes. He built a charcoal plant and Ford Charcoal was created (later renamed Kingsford Charcoal). Today, Kingsford is still the leading manufacturer of charcoal in America.

Other examples include straw, which is a by-product of grain harvesting. In the old days, that straw used to get fed to cows that produced primary products of milk, meat, and leather. My parents and their parents used one of the cows' better known by-products to fertilize their gardens.

My wife recently started throwing broken-up egg shells—a by-product of breakfast—onto her vegetable garden because, apparently, they are an environmentally friendly way of deterring snails. Working in the garden and mowing the lawn also have a useful by-product of using up calories. I write a blog, which is largely a by-product of the research I do for my consulting and writing work. Some people say that it could also be used metaphorically to fertilize a garden.

So, back to software development. What do you currently produce that you consider waste, but which could be used as a useful—perhaps even profitable—by-product? It's not such an easy question to answer, is it? If the answer were obvious, then you'd already have done it.

Let me give you a few examples I've observed in my work. The first is from a software company that produced software used by banks. One of the downsides—a waste, as they saw it—of producing their product was that they had to spend several days training their customers every time they released the latest version. To make matters worse, the training was intense, dull, located in a part of the country few folk visited enthusiastically, and regarded by most as an unpleasant chore.

That changed, though, when a new customer services manager joined the company and decided to turn the crab into crabmeat. He realized that training was one of the few times that the users of his product—all from many competing banks—were in the same location at the same time. He asked whether there was any advantage his customers would have by being in the same location as their competitors. He couldn't think of anything, so he made a point of speaking with his customers and discovered that they considered the most valuable part of their work to be the after-hours, informal chitchat they had over lunch, dinner, and in the pub after the training course. His crabmeat moment came when he figured out how to change the training into a customer symposium with plenty of formal and informal time, during which his customers could take advantage of their time together and also receive a slimmed version of the training. The customers loved the new format, and a wasteful, unpleasant experience became a useful and profitable one. It's rumored that a few marriages broke up as a by-product, and a few more started.

A friend of mine works in the software division of a company that makes components used in consumer electronic gadgets, such as phones. For years, he's built simulation and tested software for his internal colleagues who design, build, and test the hardware. Recently, his colleagues in marketing have discovered that their customers are eager to use the software in their own development work, so he's modifying some of the internal tools to be part of the product they sell to customers. The software not only makes their hardware more competitive, but it also helps get their customers' products to market sooner, making them more money.

Finally, on a more altruistic note, one of the most beneficial by-products I've seen in our industry is the huge number of software development folk who happily and freely share their stories, lessons learned, and knowledge with others in their local and global community. StickyMinds.com is a good example where useful ideas and experiences—a by-product of the authors' day jobs that would otherwise have been wasted—are packaged up and shared with thousands around the world. I'm also thinking of the many local user groups that have popped up in recent decades, aided by the Internet. In Scotland, where I live, there are a half-dozen active user groups where folk meet to share their day-job knowledge and where tech celebrities run free public sessions when they happen to be in the area consulting, training, or attending conferences.

So, my challenge to you is this: Look at what you and your colleagues currently do in your day job, and ask yourself what is currently considered a waste. Then, ask yourself if it could be turned into a useful or profitable by-product. It won't be obvious. I never tasted crabmeat until I was in my late twenties—despite its unappreciated abundance.