One of my favorite apps is Evernote.
I think Evernote as a company is truly transformative in terms developing applications to help people to remember better and also help in organizing your thoughts more efficiently. Taking notes has not been so fun and easy. If you are not a user yet, you should definitely try it out.
Another nice thing I like about Evernote is its humble beginnings, its story of almost being a failure but persevere and became a successful company that raised more than USD250 million in a billion dollar valuation.