Is there any site where to look for a data modeling inspiration?

Here's my problem: I'm about to design and implement quite a big sales module on top of an existing business (web) application. What I need is basically this - a complete e-commerce layer without the public part of it (I don't need a cart, payment开发者_C百科 gateways etc.). I'm going to build this thing from scratch since I'm not willing to hack any of the existing solutions (I'm using Rails, just to complete the picture). I've been thinking about the whole thing for a while and checked some of the existing solutions for inspiration about how to kick-off my data modeling. I'm pretty far with the model now, however, I can't resist to have a feeling that (at least to some extent) I'm reinventing the wheel here. I mean, there have to be thousands of data models out there which are similar (if not identical) to mine. I tried to find some of them but with no great success. What I want is not a complete database model, just a logical model that I can use as a checklist when doing my own thing. What I found so far is just this site which is more of a collection of database models without any description or reasons behind the models at all.

So, my question is: Do you know of any sites where to look for a data modeling inspiration?

EDIT: Since none of the answers so far provided me with what I am looking for, I'll try to refine my question. I'm not looking for any particular database diagrams (and as I mentioned I'm not interested in reverse-engineering of other existing systems), nor do I need to study the subject of data modeling in general. What I'm looking for is something like an online version of this book. It's just hard to believe there's nothing like that out there.

Thank you all, anyway.

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This site has been mentioned on stackoverflow before, and has lots of relatively systems agnostic relational database examples.

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r937.com has a good introduction.

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Domain-Driven Design (found at Google books) if you want to delve deeper than database design and get into analysis and modeling of a domain.

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OSCommerce is an Open Source online shop e-commerce solution. If you get the sources I guess you'll get the db creation scripts as well so you could look into their data model.

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May be you can have a look at the Apache Ofbiz project. Its design is based on the data model resource book you mention. They have an online demo here : http://demo.ofbiz.org/ecommerce/control/main