The problem I have with these tools is that the diagram it produces is really not that great. I guess it tells you what models you have, the columns they have, and whether a model is tied to another one... but not much else.<p>Here's the thing: I already know how many models I have (I just look in app/models) and which columns back them (I just look in db/schema).<p>The thing I often want that 1) ActiveRecord doesn't give me and 2) I haven't seen in any tool yet is a diagram of the relationships. So I have two models, A and B, and A has many B. How do you diagram that? Typically I've seen arrows: B points to A, with the words "has many" written next to it. The thing is, if I have 30 models in my app, I'm not going to be able to read this at a glance. Words are too small. Diagrams are meant to be rough pictures.<p>The way I visualize this in my head and consequently diagram this on a whiteboard is, multiple instances of B point back to A. It's easy. If you have a has_one instead, then only one B points back to A. Makes sense right? No one does this. I often wonder why.