Test your logline here before spending months in development. This is not a contest, there are no prizes. However, you WILL get invaluable help in sharpening your concept and refining your logline. Make sure to start here.
For years I've commented on loglines and such in the Save The Cat forum (though it hasn't been busy of late and that prompted me to look elsewhere). I was also a member of The Left Door workshop and recently stepped away from it as I pursue other avenues than spec scripts.