Agreed. I keep a journal of ideas, even for very rough ones, that I come across. Many times I read an article or deal with a certain subject at work and ideas f

Agreed. I keep a journal of ideas, even for very rough ones, that I come across. Many times I read an article or deal with a certain subject at work and ideas for businesses start forming. Key for me is to write them down right away, so my mind is clear for new ideas. When I have some time, I go back to my journal and start writing out those ideas, thinking through features, sketching. Then I might not touch it for a month and then do another round of refinement. After a while, you end up with a great archive of projects, and since you've been chewing on them for a while you have a good idea of what's worthwhile.