there's also partyquests. Doesn't guide you like questhelper, but allows you to view your everyone in your parties quests as long as they all have it installed. It doesn't allow modifing others questlog, but you are able to share others quests with yourself last I used it. It was part of cosmosui. It gave you a better notification of other members quest progress then I have found in other addons, big message up at "spell not ready" location to say completed, #/# collected, and so on. I don't think I would switch to partyquests after using questhelper, as it tends to help a lot more then partyquests.