No such thing although there have been efforts to create one - BUT there are a few websites that between them cover a massive part of the market.
The annoyance that we (as volunteer ride organisers for Macmillan fundraising events) have is the start-up site that finds our events, lists them with inaccuracies .. - and then tries to hold us to ransom to "introduce" entries. Or the sites that have listings that don't have the year in the date ... and are often out of date (as in being in a previous year)
Rob