If you are looking to duplicate just the questing functions of Carb, here's what I'd recommend and currently use:
Grail
This is a very nice database with most (if not all) quests currently in game. I personally haven't run across one that it was not aware of yet.
Wholly
This uses the Grail database and with it, places quest markers on the world and mini maps to represent where quest's are. Everything from Dailies to item drops etc.
TomTom
aka Crazy Arrow
It has a fantastic ability to automagically create a waypoint to the nearest tracked quest objective in the current zone.
Who Framed Watcher Wabbit
My personal choice for a nice, easy to use, Objectives tracker. Try it, you'll like it. That's all I can say.
QueLevel
Tiny addon adds quest level to the Objectives display.
Hope that helps you out.