Some of you may be familiar with this feature from the virtual world 'There'.
I'd like to suggest the ability to lend an item to another person, with the ability for the lender to retrieve them at any time.
Hypothetically, you could loan someone something directly from your inventory, by dragging and dropping it onto another person or their profile. This would then present you with a dialog to "Give", "Loan", or "Cancel" *(bonus: cancel doesn't currently exist even now, so this could add that ability as a bonus feature).
Add a checkbox to the object editor panel somewhere near the "Anyone can copy" checkbox, to specify "anyone can borrow this object" so that someone could come across the rezzed copy and borrow it without having to ask (obviously only if the owner checks the option to allow this).
This would also be a great way to let someone try something before buying it.
One way to handle the user interface would be to add two new top-level branches to the inventory, one containing objects you are borrowing from someone else, and another containing a list of objects others are borrowing from you.
When you borrow something, a placeholder would appear in both the lender and the lendee's respective folder so that the lender can right click the object and take the item back, or the lendee can return it.
This would probably be a bit difficult to implement, so I wouldn't put it at a high priority, but it would be nice to see someday =)
Please share your comments, suggestions, etc.
Thanks for reading
-- Kex
Voting Proposal: http://secondlife.com/vote/get_feature.php?get_id=175