An even better one is
http://www.drbo.org(Douay Rheims Bible Online) it's easy to remember.
That one specializes in its fast search capability. I met the man who put it together -- he's a traditional Catholic and a very experienced computer programmer. He specializes in language parsing and algorithms.
So I doubt any other online Douay Rheims will be quite as fast, as far as searching it goes.
Matthew