Thoughts on "negative indexes"

[beckphotonik]

MinimServer indexing is great if you know what you want but is/can/should there be a way of selecting an index to exclude rather than include items.
For example, I am currently going down the Genre/Subgenre tag route to manage what is displayed on my control point. Rather than select say: Classical>Romantic>Concerto>Piano, it would be nice to be able to say e.g. Classical but Exclude Baroque>Violin and be presented with a list of what's left.
I would appreciate your thoughts and suggestions on this.