In our barn's tack room I have...
2-3 Saddle pads I own, but like 25 others for lesson horses.
Lots of extra girths (those are mostly for the lesson horses)
Grooming supplies (brushes, hoof picks, etc.) on a big shelf.
Some half-chaps & extra field boots.
Lots of halters, lunge lines, & extra stirrup pads.
Bridles (of course!)
& in this other room next to it we have lots of blankets, fly masks/sheets, first aid kit, MTG, some buckets, hoof oil & polish, boot polish, etc. & a trail bag.
probably missed some stuff but oh well, lol.