Sequels are the ultimate cash cows, and people roll their eyes when sequels roll into cinemas. However, some movies scream "sequel", and, if done right, a sequel would be fucking awesome. Some movies even scream a number of sequels.
I'll keep all entries on this list, and maybe one day we'll see sequels for all of them :)
They already announced that X-Men First Class is getting a sequel. Same with Anchorman, Sin City and True Lies. A sequel to The Italian Job will be a total rehash, since the original 60s classic didn't need one.
Added you here: http://www.listal.com/list/2011-films-top-10