Not having read this thread I don't know if it's been suggested already, but I'd really like a character tracking system. It could use something like the alert system, or the outliner, but you should be able to track anyone you desire. A tracked character would be listed on the main screen somewhere and important details could be checked via a tooltip, and a click would take you to the faimly tree/ledger. In addition you should be able to set it up to alert you to certain changes, like them becomeing of marriagible age, gaining/losing heir status, or dropping below a certain loyalty etc.