The first one is about MVP and dependecy injection and threading.

And Allthough it's not perfect it does explain a lot. However, agian the example is to simple and therefor more work needs to be done to really understsand the concepts.

The next one is about SQL-Server interview questions.

A bit different from the one on Denis' page but still contains a few usefull tips.

The third and last one is an introduction to Object oriented programming concepts.

What can I say. Sometimes a bit simple. But simple can be good.