As the Service Hub picks up more traction, it'd be great to include functionality to associate new or existing records to conversations directly from within the inbox (similar to how you do in within a record's view).
At the moment, we're quite limited with front-desk teams not being to associate records and contributing to friction in adoption by adding unnecessary clicks to their customer experience journey.
(I've included a screenshot showcasing the lack of "Add+" compared to the ticket record view)
Conversations Inbox Associations View
Ticket Record Associations View
This pertains to both the standard objects, but also custom objects within the inbox.