I have this weird obsession with making lists- of things I need to do, things I want to buy, or people I need to
Available for almost any platform you could think of (OSX/WIN/IOS/BB/ANDROID), Wunderlist is a gorgeous looking app that is also packed with lots of features such as syncing lists across devices/platforms, as well as a sharing lists with multiple users. Before using this I used Google Tasks for my to-do list, and Evernote for my regular lists. Now all I need is this. I highly recommend you guys try it yourself.
Links:
http://www.wunderlist.com/
http://evernote.com/