From the DotNetButchering blog there's a recent post looking at design patterns, more specifically ones you might be using and you don't even know it.

Rise your hands if time ago (or even now) you stood literally in trance listening to your friends or colleagues talking about design patterns. [...] Anyway I felt better (and also my ego did) when I found those Design Patterns were no more than ways to solve common programming problems, and as I was programming since 2 or 3 years, I had already discovered some of them myself.

He points out two patterns - the strategy and factory patterns - and gives code examples (and UML diagrams) to show how they work.