If you have used Rails for non-trivial applications, you have probably run into a lot of “Hmm, what would be the best way to do this?” moments.
As soon as you tread off of the simple path, you need to think :)
Rails Recipes has been a saviour for a few of the items that I care about. The Wiki doesn’t cut it. A co-worker spent a few hours working on ideas from the Wiki. Then he cracked open Rails Recipes, found an exact solution, and it actually worked right away :)
The book is in beta form now, and will shortly be finished. I am sure there will be several versions in the future as Chad finds more and more useful ideas.