I'm looking forward to Inception the most, it being an original blockbuster considering it's not a remake, a sequel, or a franchise picture. Plus, it's a Christopher Nolan movie, and everything I've heard about the film gets me more and more excited every time I hear about it.
Other than that, I'm mostly indifferent to the rest of the movies coming out this summer. I have no interest in Robin Hood, regardless of the fact that it is a Ridley Scott/Russell Crowe movie, and I gave up on the Shrek franchise after Shrek 2. I will see Sex and the City 2 out of curiosity since I enjoyed the series and the first movie, even though I don't really have a huge desire to see further adventures of that universe.
The A-Team looks like your typical mindless summer diversion, and while I'm not anticipating it, I will see Toy Story 3 for nostalgia sake since I have fond memories of those movies. The Twilight Saga: Eclipse does look interesting, and I'll probably see that out of curiosity mostly because of David Slade's involvement as director. Slade directed the fantastic Hard Candy and the solid 30 Days of Night. I have no desire to see The Last Airbender, but Predators does look interesting. The Expendables is definitely a must-see, even though it'll likely just be more of the same (i.e. mindless fun).
Summer 2011 looks a lot more interesting, with The Green Hornet in January (regardless of the bad hype, I'm intrigued), Scream 4 in April, Thor in May, X-Men: First Class (the fact that it's a collaboration between Matthew Vaughn and Bryan Singer has me stoked) in June, Green Lantern also in June, Harry Potter and the Deathly Hallows: Part 1 in July, Captain America and Cowboys & Aliens also in July, Contagion in October, and Brad Bird's Mission: Impossible IV in December, not to mention Duncan Jones' next film Source Code also out sometime in 2011.
Yeah, 2011 looks a lot better in comparison.