nb is very good and I've used it extensively for the last 2 years or so. I especially like that you can just throw it a url and it will create a bookmark as well as download a markdown version of the page (using pandoc to convert I think?) This is very useful, especially when links go stale

Also, if you install notational-fzf-vim (https://github.com/Alok/notational-fzf-vim) and point it at the nb folder, searching through notes becomes a breeze. Additionally, you can use vim-markdown-composer (https://github.com/euclio/vim-markdown-composer) as a previewer for markdown in vim.