The fsuniverse site is a good one, but there's no neat list there. For a concise summary, you can use the United States Figure Skating Association's website at http://www.usfigureskating.org/Events.asp. The thing that's hard about the USFS list is that it's a list without any qualifications, so you can't tell which are higher and which are lower level competitions.

Something related that may help you is this list of all skating that will be on US tv, and when: http://heatherw.com/mk/sch.htm