Category Layout and overall flow

[QuentinJS]

When it comes to Categories is it possible to say have a left panel/table ect that looks like this...

Categories
- Cars
- Travel
- Kidz

Then clicking on Travel, the list would show as....

Categories
- Cars
- Travel
  - Calgary
  - Toronto
  - New York
  - England
     - London
- Kidz

If so how easy is it to do this?  

Or in general, how easy is it to change the flow and over all look of the gallery?

Thanks

[Tarique Sani]

You can create a left menu tree with the categories and add it as a mod BUT with people using CPG with 100s of categories I doubt that this will be ever main stream in CPG