I apologise, it seems this has been talked about a great number of times! Ah, well, I'm glad I'm not the only one to think so!
I've also been looking at the ideas of Dumbledore and his ramblings under the potion...his worst memory? Ooooh...Maybe in his pensieve? (that is one of J.K's better ideas, I love that word, it's a very good pun) and also the idea of Reg Black (He was one of the first people I thought of with R.A.B...who else would have those initials who has already been alluded to in the book?) was rambling around at the end of the last book. Some very good ideas flying around!