I would like to see the ability to sort the quest list in the compendium by quest chain. It would help let new people know if they need to be "flagged" for a certain quest. It would also be helpful to vets to quickly check if a character is flagged or not. It does get confusing when you have multiple characters and some of the TR'd to remember who has done what. Not that you can't do it now, it would just be easier to see it all at a glance.
(forgive the dashes but it was the only way I could find to keep the format)
Eyes of Stone
----Framework
--------Diplomatic Impunity
Plane of Night
----The Vault of Night
--------Tharashk Arena
--------The Prisoner
--------The Jungle of Khyber
------------Gateway to Khyber
--------Haywire Foundry
Although this may be asking way too much but it would be great to see the status of other characters on the account. So if your looking for something to do and you see a lfm for a quest you can check to see if one of your other characters still needs it.