I backed light table because I wanted to play with it, I backed penny arcade because I want them to do more projects and instead of work for hire, I often back books that wont get published unless there is a campaign. In every case there is a sense of camaraderie that I do not experience buying something on Amazon, it is personal, however in every case I also get some piece of content that benefits me.
* I am assuming you mean a kickstarter style project, if you mean something completely different then ignore the above. You may also not be getting answers because you didn't share any details about what you are trying to do.