Where do you get the ideas to create creative and useful applications?

Question

It's so dificult to me thinking about something that hasn't been already done.

Answer 1

@Justin
right to the point.
NECESSITY.

Answer 2

necessity. if you find a need, fill it.

Answer 3

Look around you.
While you study, work, buy things, searching for something, playing around...
You'll find that something is missing or is not as good as you can do it.