It would be nice once we have the ability to place holds on multiple items attached to one title if the patron could define which item them want first. So if they place holds all of the items attached to a TV series on DVD for example. They want to be able to say I want Disc 1 before Disc 2 and so on.
Nicole mentions items connected to the same record, but Cascading Holds could also be something to think about accross records, when you have e.g. a series of books that patrons might want to read in sequence. Series statements in 490 (in MARC21) would come into play here, I guess: https://www.loc.gov/marc/bibliographic/bd490.html