Workflowy is one I came across just recently and I am intrigued by how it works. It was recently named to the AASL top 25 web 2.0 tools of 2013. I decided to try it to organize my grant writing schedule. I love how it looks.
It has these little bullets that can be hovered upon to add notes, change concept, etc. It's awesome! It gives you the power to hide notes and information so you can refer to it later.
I created a board that was for my grants. It's a little hard to see, but the site has the capabilities of expanding and decompressing the information you are adding. Signing up is free, and it's like dropbox. If you invite others to join and they do, you get more space. I have been using that aspect of dropbox for ages.
This site is very easy to organize and plan your day. I suggest looking at it. You might find it works for some of your needs.