iOS: Paper is easily one of the best drawing apps on iOS, and recent updates have added in the ability to write to-do lists and other notes. Those new features were welcome, but made it a little tough to navigate the app. Thankfully, a new and improved sidebar fixes that. Paper has gone through a lot of iterations since it first launched, and eventually ditched the notebooks in favour of "spaces". Now, those spaces are called grids, and you have access to all of them from the sidebar. The sidebar is a nice improvement over the the previous interface. You can also now search from the sidebar, which is pretty useful if you have a lot of different notes. If you haven't used Paper in a while, it's worth another look, and this update makes it a bit easier to use in general.
Paper (Free) [iTunes App Store]