Offer voice / audio notes.
Several other comparable applications (SpringPad, Evernote, Note Everything) offer audio recording capability. If Diigo were to offer that as well, I would be able to get rid of the others, and Diigo would position itself as the clear leader of synchronized note-taking applications, as far as I'm concerned.
Completely agree, that's the only feature that i am missing ! Sometimes i'm in my car and want to take some notes, so i use a voice recording app on my android phone, but i'd prefer to have all my "notes" gathered at the same place : diigo.
Would be great !