I honestly don't see how they could have a movie or any spin-off's of Angel after that ending.
Going back to the first couple episodes and remembering how much I hated Lindsay for being a smarmy little bastard, I'm glad he got killed by a 'flunky'.
I, too, missed the Shotgun of Doom. He had the knife pop out of one sleeve, WHY NOT THE SHOTGUN OUT OF THE OTHER?! (I don't know how, magic or something)
Why hasn't Angel signing away the Shanshu prophecy been brought up? I thought that was one of the best parts. One of the most important things in the entire show, pretty much the one good thing Angel may have had to look forward to, got signed away so they could hurt the Senior Partners a little bit.
EDIT: Damn, someone posted before I could finish my post. But still...
Oh, and I loved the Pylea fight reference ("You take the 3,000 on the left")