The official definition of rec.roller-coaster is:
rec.roller-coaster -- Roller coasters and other amusement park rides.rec.roller-coaster is an unmoderated newsgroup which passed its vote for creation by 184:72 as reported in news.announce.newsgroups on 21 July 1991.
This newsgroup is for the discussion of any amusement park rides, including (but certainly not limited to) roller coasters. Other topics include park operating times/season schedules, admission prices, latest attractions, future expansion efforts, etc. You might also want to read rec.parks.theme for pertinent discussions.