A design pattern is a solution model to a design problem. Here a list of sites I often look at:

http://www.welie.com/patterns is a review of most web design patterns with one by one explanation and screensots.

http://developer.yahoo.com/ypatterns is the Yahoo design pattern library. Very good explanations and concrete exemples and best practices.

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A worldwide Logos database.
You can search by autor, category, country, history etc.
http://www.brandsoftheworld.com/

A database with great print Ad campaigns.
It’s like the Taschen book Advertising now! Print, but online and free.

http://adsoftheworld.com/

A database with online copies of stunning interactive web advertisings and communication concepts.
You can search by agency, brand or category.

http://www.bannerblog.com.au