Another vote. Easily editable, searchable via Spotlight or similar solutions; easy to present in a formatted way especially if you keep notes in Markdown; easy

Another vote. Easily editable, searchable via Spotlight or similar solutions; easy to present in a formatted way especially if you keep notes in Markdown; easy to edit on the go with something like PlainText (http://www.hogbaysoftware.com/products/plaintext http://www.hogbaysoftware.com/products/plaintext); and, of course, easy to have available anywhere with Dropbox.