Personal item displays!
-Weapon racks, display cases, mannequins, shelving, hooks, etc to show off all your favorite items in your Garrison.
Check these pictures out. This is from WoTLK era, in many of Dalaran's stores.
There should be a Garrison Trophy Room or at the least some area(s) throughout the buildings where you have the option to display your personal possessions, such as Weapons, Armor, Toys, and Items, just like how the Archaeology displays are. Each item could display its item-link upon hover-over and maybe even things like its age (how long you've owned it)
-A 'Skin-rug area' for the time you slayed that rare-spawn beast, for your Inn.
-Some 'Racks' and "Target Dummies" for your trustworthy old Armor/Weapons, inside your Barracks.
-'Shelving' for your Toys, in your Pet Menagerie.
-'Trophy Mantles' along various walls, for displaying your Legacy and Feats of Strength (as little medals/statues).
-Yet another reason to farm old content: "Gotta get that sick shield from Icecrown Citadel for above my Inn's fireplace" - said the Warlock
-Content that can be obtained, farmed, and collected from beginning to end. "Do I want the display the pelt of that first Pig I skewered in Durotar as a noob, or that massive, hulking-red Feltusk Boar I've just slayed in Tanaan?" ... "Definitely the Pig".
-More Customization: Who doesn't want more customization?
-New quest/daily content that's simple but effective for encouraging socialization: Quest could read, "View 3 other player's Trophy Rooms" for whatever reward. Rewards could be different types of displays and more areas to display in (like plots on the Farm), to name a couple.
-Storage: These areas could also act as additional storage for players whose bags/bank/void are strained. Just owning a single set of each Tier for your class, is almost 100 bag spaces!
-Maybe this is going about it the wrong way; by proposing yet another reason to stay inside your Garrison, when the call should be for further incentivizing getting out of it.
-Potentially resource-consuming undertaking: by having to create unique item displays for a large percentage of items in-game that have no literal display other than their icon.
-Justification to commit resources could be lacking: Maybe Collectors are just a tiny slice in the pie of WoW's populace and so it'd be "too much for too few".
Just a thought.
Personally, I'd enjoy this and would welcome this "content" as long as it was extraneous to the normal allocation of resources for (Questing/Dungeons/Raids).
What about you, fellow MMO-Champion'ers?