While browsing YouTube I managed to find all the deleted scenes on the Harry Potter and the Half-Blood Prince DVD.  You can check them out below.

The first half or so are mostly conversations between Harry and Hermione about how and why Draco is disappearing from the castle grounds.  After that we get a disturbing story from Dumbledore, the extended pre-climax sequence I posted earlier, and some extended moments between Harry and his friends at the end.