Here are a bunch of shrines and what they do!
Mana Recharge Shrine +400% mana recharge rate
Armor Shrine +100% Defense
Combat Shrine +200% to Attack Rating, +200% min and max damage.
Resist Fire/Cold/Lightning/Poison Shrine +75% to resist fire/cold/lightning/poison
Skill Shrine +2 to all skill levels
Stamina Shrine Unlimited Stamina
Experience Boost 50% more experience per kill
Refill/Health/Mana Shrine Fills health and Mana/health/mana
Portal Shrine Opens a portal to the Town in the act
Fire Shrine All players and monsters lose 1/2 current HP, Fireballs
Monster Shrine The nearest monster becomes a Unique or Champion monster
Gem Shrine Upgrades a Random Gem or Skull in your Inventory or gives a chipped Gem or Skull
Exploding Shrine Gives player 5-10 exploding potions and tosses out 5 exploding potions in random directions/distances
Poison Shrine Gives player 5-10 Poison gas Potions & Creates ring of Poison gas around shrine