Valve Oil
There's nothing more annoying than a sticky valve. Thankfully, the vast majority are easily rectified with an application of some valve oil. There are several brands to choose from - Blue Juice, Al Cass and Rocket are all popular. The rocket offers the best value for money.
Great for getting all those fingerprints off when you've got a page worth of rests!
Cleaning Brushes
Essential for getting to those places that hands can never reach! Brushes.
Because there's nothing worse than being stuck in the wrong key.
Apologies to the rest of you, but only a Trombone Player appreciates a well oiled slide!
Only important really for lacquered instruments, a valve jacket helps stop the finish reacting with sweat as it does naturally and preserves the finish for much longer.
Springs, Washers and Valve Guides
Just in case!