You can try reddit -- not the main reddit, but a technical subreddit will usually get you some constructive feedback. For example, if I wrote an app in Python,

You can try reddit -- not the main reddit, but a technical subreddit will usually get you some constructive feedback. For example, if I wrote an app in Python, I could post to the python subreddit to get some better feedback than any of the other ones. You'll have to weed out some of the trolls, but it's still worth the time. I have also seen some good feedback come from posting a link on Twitter. Usually just the people I know will actually try it out, so the feedback is honest and straightforward.