The Folio is a tool for Dungeon Masters to homebrew monsters, manage their notes and handouts and create their own adventures for roleplaying games(RPG) like Dungeon and Dragons. It includes an Assistant to develop monsters, items, encounters and maps. You even have a mind map like tool to bring it all together.
While you can use the Dungeon Master Folio in any browser, note that you can use it as a Web App on your iPad / tablet as well.
You are new? No problem, just register and go.