I am unsure how much work this would be, however, it would be extremely useful to be able to have a pane (say on the left hand side) similar to the Explorer, but that lists all the lines ( or maybe the first few letters of the line) that have bookmarks on them. And to allow you to navigate your bookmarks in this fashion as well (by clicking on the appropriate line in the "index").
Because of Hex-Editor uses Bookmarks also, I planed to do therefore a new plugin to manage them.
But I promise nothing when you this will be available.
This function is *very* important to me, as well… I use bookmarks extensively in my day-to-day work, and the absence of any ability to select which bookmark I wish to return to, is the sole issue which is keeping me from using notepad++