I'm looking for a good online resource of software patterns. Preferably something with a comprehensive selection and concise well written explanations, not just a collection of links. .Net examples would be nice, but not essential.
You might also want to read the book .NET Design Patterns.
Some of the books above I have read and can certainly vouch for.
I recommend Head First Design Patterns book from Freemans. These are general design patterns applicable in most OO languages. I recommend this book as an introductory book to design patterns. After this book the GOF book would be another recommendation (but not as a first book).
Here is a descriptions of Design Patterns
I thing this is a very good page for reading and learning about design patterns
To see real world examples of patterns implemented, why not grab an open source .net project such as Paint.NET or CommunityServer and have a look through the codebase? You could also get Reflector and have a look at the source code for the base class library.