Interactions With Other People

Offer To marry a member of their house to you (Can Gain an alliance)
Offer to marry a member of your house to them (Can gain an alliance)
Offer Hostage
Demand Hostage
Exchange Hostages
Sway (Get them to try and like you; takes a year)
Offer ward (Give them your child to raise for you)
Offer guardianship (Offer to raise their child for them)
Grant Titles
Seduce (Takes a long time)
Romance (Takes a long time)
Wage War

Schemes (Can only do one at a time)

Murder
Learn Language
Learn Secrets

Activities and Decisions

Invite Knights ~ Up to 75 gold
Invite Wet Nurse ~ 15-150 gold
Invite Physician ~ 15-150 gold
Grand Tour ~ 150-400 gold (Journey Across all the areas in your realm to improve peoples opinion about you, as well as learn new things)
Grand Tournament ~ 300+ Gold (Hold a bunch of events and competitions to gain fame, opinion, prestige, new people to serve you, etc)
Grand Wedding ~ ??? Gold (A Large wedding between the character and their significant other)
University Visit ~ 40-110 Gold (Either study and try to improve your education and skills, or party non stop)
Hunt ~40-130 Gold (Go on a grand hunt for the sake of honor, prestige, befriending someone, seducing someone, releasing stress, or murdering someone.)
Vacation/Pilgrimage ~ 40-130 Gold (Travel to a important destination for a journey that can basically result in anything, usually gives a bunch of decisions)

Purchases

Invest in the military ~ 45--100 Gold
Buy favor with the pope ~ 250 Gold
Build castle ~300
Build temple ~ 300
Build City ~ 270
Build Spice Market ~150
Build Cattle Pasture ~150
Build Farm ~95
Hunting Grounds ~95
Build Barracks ~ 150
Build Milita Camps ~ 100
Build Stables ~ 150
Build Blacksmith ~ 150
Build Guild ~ 150
Build Trade port ~ 150