PADherder is a poorly named web application built to ease the burden of managing your collection of Puzzle & Dragons monsters. Track what monsters you own, what levels they are, what evolution materials they need to evolve, and various other things. The idea is nothing new - there is a quite capable Google Docs spreadsheet freely available that I shamelessly stole the idea from. The goal of PADherder is to expand upon the concept while being both faster and easier to work with.
Here's my shameful collection of monsters. Click the 'Sets' and 'Teams' links to see those pages.
Once you have registered an account you can get started on adding your monsters, creating teams, managing evolution materials, finding friends, and... probably more!