Your choices:
Spiderman 3
28 Weeks Later
Shrek the Third
Pirates 3
Knocked Up
Hostel 2
Ocean's 13
Fantastic Four 2
Evan Almighty
Live Free or Die Hard
Sicko
Ratatouille
Transformers
Harry Potter 5
Hairspray
I Now Pronounce You Chuck and Larry
The Simpsons Movie
The Bourne Ultimatum
Rush Hour 3
Superbad

Mine are:

20. Hostel 2- Didn't see the first, don't care to see the second.

19. 28 Weeks Later- Hated the first, and while it looks cool, ain't excited to see the second.

18. The Simpsons Movie- The show's fallen hard and the trailers ain't funny. I love the characters, but ain't excited to see this.

17. Sicko- Love the subject matter, don't like the documentarian. Will probably see this despite reservations.

16. Rush Hour 3- Didn't see the second one. This trilogy just can't get me excited. Still, the trailer looked funny.

15. I Now Pronounce You Chuck and Larry- Dumb looking Adam Sandler comedy, but this one has Kevin James, who is hilarious.

14. The Bourne Ultimatum- Never saw the first, liked the second, am kinda looking forward to the third.

13. Shrek the Third- I'm not the biggest Shrek fan, but they always provide me with some cheap laughs. I'll probably see this despite hating on the last two.

12. Hairspray- Not my favorite musical, but a hell of a cast, great source material, and movie musicals are always either really good or not at all. Should be interesting.

11. Superbad- That Apatow/Rogen team can't do much wrong in my mind right now. The trailer looks funny, and I love the cast.

10. Ocean's 13- So Ocean's 12 wasn't good, I think we all agree. This one looks a lot funnier, like a good return to the fun of the first one.

9. Evan Almighty- Despite budget and my disappointment with the first, Carell can do no wrong, and the trailer looks very funny.

8. Pirates 3- I was somewhat disappointed with the 2nd, hopefully the 3rd will tie it all together in a satisfying way.

7. Harry Potter 5- My least favorite Harry Potter book, but it's the Harry Potter movies, and the last two have been a lot of fun.

6. Fantastic Four 2- The first one was okay at best, but MAN does the trailer look great.

5. Spiderman 3- I was very excited about this. I mean, did you SEE the trailer? It was advertised as the event you didn't want to miss, and I didn't want to miss it.

4. Ratatouille- Pixar + Brad Bird = inevitable brilliance. No chance that this movie isn't great.

3. Knocked Up- I always really look forward to one comedy a summer. This is the movie that my comedy hopes rest upon. Which is good, because it looks terrific, and everyone who's seen it has raved.

2. Transformers- Fuck it, this is what the summer is about for me. The trailer and special effects look fucking awesome.

1. Live Free or Die Hard- So I'm sure this will disappoint me. I'm sure of it. But with the trailer to the 4th in one of my all-time favorite trilogies being SO cool (I mean, he uses a car to take out a helicopter! FUCKING AWESOME!), I can't help but be more excited about this than any other movie this summer. If it delivers... well, I don't want to jinx it. But I really REALLY hope it lives up to the three before it.

Those are mine. Now do yours.