There are many beginning and advanced Ruby on Rails books available, from the authoritative Agile Web Development with Rails to the cookbook-style Rails Recipes. However, healthy guidance for intermediate-level developers is lacking at best. Ironically, this is the most crucial stage in the process of becoming proficient with Rails because one must begin to learn why, not just how. Eldon Alameda's Practical Rails Projects (Apress, 2007) effectively fills that gap. I know Alameda from our local Ruby User Group and spoke with him frequently while he wrote this book. His expertise with Rails definitely shines through in the hefty 621-page volume.