For instance, you want to implement authentication. Right now the best thing you can do is head to railscasts, see what the latest screencast is for authenticaiton. Ah, november 2010. Might as well be ancient history! Perhaps there's a newer, easier, more-accepted authentication gem out there. Or maybe not! You just don't know. So what's next, maybe check some blogs, github, do some date-specific searches on google, etc.
If you or someone else had a site that basically said, "here's the current accepted practice for implementing authentication, and here's why", then that saves so much time!
All I can hope for is that with some community involvement, ScaffoldHub might become something useful in the middle: not in depth tutorials, not a code repository, but a series of helpful working examples.
I certainly can’t do it alone!