Today Stephan Schmidt threw the first public release of his new PEAR package Services_Delicious, which allows to communicate with del.isio.us through PHP pretty easily. His announcement shows a pretty little example. Since I'm currently on a del.icio.us trip (I recently migrated all of my bookmarks there), I like that thing pretty much, also I did not come to try it out, yet.
Directly adding your entry to del.icio.us while posting.
Direct integration into the sidebar, with customization through the admin environment.
.o0(Wow, what a link flood...)