As a JCer I like to keep a certain number of each type of cut rare gem on the AH at a time. (I do much the same with enchanting mats but in greater bulk).

To do this at the moment, I scan the list of existing auctions looking for mine, and then adjust the count manually. It would be handy to be able to have Appraiser handle it automagically.

When/if multiple stack sizes are added it could be a per stack size setting for each item.