As part of something else I've been working on, I would like to be able to view the links associated with a set of bookmarks tagged in a particular way excluding the display of links that are also tagged with a particular term.
As far as I know, delicious doesn't support queries of the form del.icio.us/userName/thisTag+thatTag-butNotThisTag.
Now, I'm not really bothered if delicious returns links that are tagged with butNotThisTag, as long as I can prevent those links that are tagged this way from displaying.
So here is a deliHideTag bookmarklet (only tested in Firefox) that allows you to highlight a particular tag on a results page and then hide all the bookmarks that are tagged with that tag.
So for example, if you go to http://del.icio.us/psychemedia, highlight for example the library tag, and click on the bookmarklet, you should find that all the links tagged with library are hidden.
(Actually, you can highlight any text on the page, and if it is found within a tag, that link is hidden.)