PAD Forum -- A forum dedicated to PAD. Find friends, talk strategy, and generally commiserate. A great resource for players wanting to learn more about the game.
Bonuses Schedule -- The bonuses on Normal dungeons (1.5x Drop%, 2x Coins, etc.) repeat on a weekly schedule. This google doc explains that schedule.
PAD X -- The 100% complete constantly updated PAD database with all the current information.
PAD Discord -- A great Discord room