That's a problem I'd love to have! I feel like I don't come up with ideas very often, and when I do they don't seem to be very good, feasible, or original.
My ideas appear often when i'm having trouble with some situation and suddenly i've look at some app on the internet that with some modifications could tackle that trouble. Often i have the same doubts as you on how good, feasible or original the idea is and often this questions makes me leave the idea behind too soon.