A list of possible discoveries by the Large Hadron Collider and the probability of each discovery being made within the next five years.
The Higgs Boson: 95%. The Higgs is the only particle in the Standard Model of Particle Physics which hasn't yet been detected, so it's certainly a prime target for the LHC (if the Tevatron doesn't sneak in and find it first). And it's a boson, which improves CERN's chances. There is almost a guarantee that the Higgs exists, or at least some sort of Higgs-like particle that plays that role; there is an electroweak symmetry, and it is broken by something, and that something should be associated with particle-like excitations. But there's not really a guarantee that the LHC will find it. It should find it, at least in the simplest models; but the simplest models aren't always right. If the LHC doesn't find the Higgs in five years, it will place very strong constraints on model building, but I doubt that it will be too hard to come up with models that are still consistent.
The list also functions as a nice overview of what's happening at the edges of our physics understanding. (via 3qd)