It would be useful to have a minimal installation option that installs only a small core set of packages. This could be used for creating special purpose, small footprint servers.
You can of course just unselect all of the stuff which is selected in the Package Group Selection screen. Unchecking all of the groups in that screen will result in a minimum installation which is about 120M of data. There has also been a number of requests for an actual "Minimum Installation" selection just as we have the "Everything" selection. I am forwarding this to a developer for inclusion in the features-request list.