Awww, I'm sorry...I know the feeling. You get all excited because you know what happens at the end, and then you realize you don't have any more to look forward to and you just think, "Well, damn.". As for what you can do now, if you haven't watched Angel yet, do that. If you have or when you're done with it, move on to Firefly and the movie that takes place after it, Serenity (in my opinion, they're better than Angel and very nearly as good as Buffy), then Dollhouse. Once you've finished them, well, you're stuck in the endless stream of rewatches like the rest of us!