Well I gues you mean beyond powder,patches, and balls.
For the caliber, you'll want a good cleaning jag, a breach scraper, a patch puller, and a ball puller, that comes to the top my my mind. A brass barrel brush is also good.
For the rifle, you'll be glad to have a flint tapper, to re-shape the battered gunflints, a wire to pick the vent hole when it gets clogged, a nice guncase to keep some of the dings off of it, a horn,flask, or some device to prime the pan, and spend the money for a range rod. Mark somewhere what the threads are on your accessories, usually 8-24 or 10-24, but I can never remember which is which. Also get something to keep your spare flints from banging around and getting dulled.
A separate shooting bag and/or pouch for each rifle will save you time and grief at some point in the near future.