I know it seems obvious, but determining when to create your own tech instead of using or extending existing solutions is tough.  Even tougher given the tendency of people to think their situations are unique instead of being "just like situation X with Y added."<p>I mean, how many times (to beat a dead horse) have you seen someone say "I wrote my own framework because &#60;insert contrived scenario that other frameworks have solved or are easily extended to solve&#62;".<p>Yes, sometimes your situation is so unique you need to role your own solution.  Chances are it's your ego talking instead of common sense.