Two ideas...

High level knight ability, at least hero. Build Keep.

Standard simple desced keep. It can be build in any 'friendly' terrain, such as Avalon, mountains or neutral parts of Losthaven. It doubles your 'keep' ability, but only for items dropped there. ie. I could train the War Band for example, leave them in the keep and go and recruit another (as an example). The keep itself is of a standard desc (so yes, all knights keeps look the same built on the same design, personalised by a 'banner of Prince Gavadel' for example). It consists of an open hall for everyone and armoury. The armoury is locked to the PC and where items/whatever can be dropped.

For everyone who can ride. Saddles.

Lost of possibilites there from standard leather to artifact and ranger skinned.