I did want it to behave as the "buttons" view in mac os classic - one-click opens the folder.
I can see it as a grid, as a fan, or as a list (I'm still using Leopard 10.5.x - maybe there are more options in Snow Leopard?), or right click it and choose "open", which still are a lot off clicks for me.
The closest I could get is left clicking on the folder together with Command Key, which opens up the parent folder... still annoying!
Well, the solution was simple:
before you put the folder in the dock, make an alias of the folder, put it somewhere where it do not get lost and then put the alias in the dock.
Voila! The original folder opens up when you click on it, instead of a grid or fan or a list...
I now have a special folder saved, where I put aliases to Downloads, My Documents, Servers... - all of them put in the dock.
Off course there are some folders that are just fine to open up as a nice fan, or grid - Applications for example...