I always wondered why Dumbledore had James' cloak as Dumbledore never needed it as he could make himself invisible without it.

One theory is that it was a similar situation in OOTP, where Mad Eye Moody lent his spare cloak to the order to stand duty. Who knows what the order was doing the first time round and why they would need it.

Another would be that there is more to it that meets the eye. I'm not suggesting it's a horcrux or anything, but it is a powerful magical object, there maybe extra powers that we don't know about that Dumbledore needed it for.

I must admit, this one has got me stumped. All the other threads, I have a basic idea of where things are going (even if they prove completely off the page when book 7 is release), I've got my direction with them. But this is something I have no clue as to why he had it.