The love test from Robot Co-op (the guys behind 43things, 43 People, 43 Places etc...):
"When we started working on product ideas, one of the tests we subjected every idea to was what if it works?
We had lots of ideas: a better answering machine, online education tools, job hunting sites, baby blogs, personalized text ads, personalized news services. Sure, we could build a personalized text ads service! But what if it works? Do we really want to run that business?
Before long, we realized we had one primary criteria for an idea we’d want to work on: it had to be an idea we loved so much that if it works, we’d be happy to work on it. Reflecting on the love test I found myself contemplating the word Amateur. The root word there is love, and an amateur is someone who pursues their interest out of love, not a hope for professional recognition or market success.
The test we were concerned with wasn’t how great a business the idea would be. It was whether we could love the work. We thought about products we admire: del.icio.us, flickr, upcoming.org, craigslist, bloglines. Some of these are going to be great businesses, but all of them have an amaeteurish edge in the best sense of that word. They look like works of love. It was the amateur roots of them, the passion behind the product, that we admired."
Full link: http://blog.robotcoop.com/2004/11/15/the-age-of-the-amateur/