I'm betting this post will recieve a lot of response but that you won't find what you're looking for.
I'm not necessarily looking for something that is ideal. Just some examples that make good use of Boost and STL and modern design techniques. If this means that the gui portion of the app is more tied to a gui framework or toolkit then that's fine.
This is generally refered to as MVC (Model, View, Controller) pattern.
I'm very familiar with MVC. In terms of MVC I'd be looking for something where at least the model and hopefully the view are using modern design techniques. My primary goal is to study an elegant and efficient design and implementation. If modern techniques are not possible for the whole application due to lack of gui libraries to support that, etc that is fine. Mostly, I'm looking for recommendations of really good examples to look at. Any ideas people have are very much appreciated... Regards, Matthew