This is the default categories module on steroids! Users can hide every category from showing up in the recent discussion list by simply hovering over the category name in the list and select "hide" from the options menu. They can be unhidden from within the module as well, by hovering over the heading and select "Unhide ..." from the option menu. You can switch between seeing the discussions from all categories or only from the unhidden ones.
CategoriesModulePlus looks exactly the same as the default categories module. So the added functionality is out of your way when you don't need it and right at your hand when you want it!
v0.2.1 fixed problem with categories as homepage and/or RewriteUrls = FALSE