I've found some books like Maguire's "Writing Solid Code" and McConnell's "Code Complete" to be helpful, but your best resources are probably the source code to systems similar to your definition of 'real'. Depending on this definition, I'd suggest looking at the source for SQLite (compact and rock solid), Apache (customizable request handling), Perl (for polymorphic data types), and Linux (a big modular system). Basically, pick any of the open source tools you use, and see how they've solved the problem you are interested in!