Here are some that I have just by looking at my history:
Dying of Curiosity**
In Cassardis, some one (I forgot who) has a quest to search for Valmiro. Should show up after the Lure of the Abyss.
Talk to Fournival to accept a quest to look over his daughter, Symone.
I believe you can get this from someone in Gran Soren. I got it after meeting with the Duke for the first time.
Speak with Mirabelle in the Castle to accept the quest.
Talk to Caxton the weaponsmith for the quest.
Of Merchants and Monsters**
Outside the eastern entrance of the quarry, talk to the peddler to accept the quest.
Speak with Chamberlain Fedel to initiate the quest.
Rise of the Fallen**
Not sure but I think this one is missable. Speak to Ser Maximilian at the Castle Gates.
Speak to Madeleine to accept the quest. I spoke to her post-game, not sure if you can get the quest before that.