not sure if what I am looking for can be done, but here is my idea:
lets say you have a recipe site and want to allow people to filter them, I'd love a visitor to have the option of clicking on tag clouds, i.e. a cloud with courses: main course, desert, soup, salad, etc. the next one with ingredients: potatoes, cucumber, etc. another one i.e. pork, beef, fish, vegetarian
and thus filter or drill down the recipes, would make it easy to check what one has in the fridge and then filter for all recipes that contain those items :-)
the perfect solution would be if one could also have negative filtering, i.e. show all recipes with meat and potatoes but without tomatoes :-)
if it can be done, i think the easiest for the graphical implementation would be to have a + sign to the left of the tag and a - sign on the right to be able to quickly select :-)
I would be really curios if this can be done...