I think a feature to insert hyperlink anchors in (text) documents would be fantastically useful.
basically to allow deep-linking into a document so that it automatically scrolls to a specified position when opened with an accordingly formatted URL.
This (together with the existing feature to add a hyperlink to any URL) would facilitate cross-references within a single document and across documents, and also from other HTML pages. Supergreat for oo documents which are embedded e.g. within a wiki!