There is , but its only really somewhere that you can submit you sitemap etc , its not like G Webmaster tools
Is there any proven benefit to the Yahoo site explorer, or if I am already being crawled regularly by Yahoo then is there no point?
There is a lot of value to Yahoo Site Explorer. You can also add a sitemap or feed and delete and duplicate sites or content if needed. It may not be as advanced as Google's Webmaster Tools, but it is still very helpful.