When your doing training sessions. Just not only focus on concepts in deep but also the following will help customers (Freshmen, Jr.Developed,Sr. Developers,Architects)

1) Try to collect stackover flow questions
Example: Most of WPF/Windows phone developers die hard to understand dependency property,attached property, difference between control template ,datatemplate,style and template , difference between label , text box

This may help. Open google.com . Type " wpf difference between "
then u will get list of key words.Google may help us.

2) Some concepts where interview people may ask frequently which is imp for development. example : Abstract class and interface.
3) what is decoupling ? Give some code example with out decouple and with decouple. How interface helps , why it helps, with simple and good example.Difference between IsEquall and == in C#

Difference between delegate and event. C# generics in deep.
How hash code helps in development??

And a news board on website:Where you all put ur updates .What course your doing?? when your expecting to release.?

Usering voting for a course AND for doubts i,e if many users not able to understand a question say: Why we need interface and abstract class or Interface and event ...
So users can vote on question : so when you think users really helps this..please do that in corresponding course .

I am sure it will help us alot.I can put more but i dont have time