Oops, cross-post. Sorry RP.

There are lots of things we hope to learn from this.

1. We expect to understand the origin of mass by finding a particle called the Higgs boson.
2. I personally want to know what dark matter is. There's 5 times more dark matter in the universe than atoms, molecules and all the other stuff we've been studying ever since we started asking questions. We foun out it was there only a few decades ago and there are good reasons to believe that the LHC will be able to produce it from scratch. That would be the first time ever that dark matter was created in the lab on earth. Incidentally, dark matter was the basis for 'dust' in the Dark Materials trilogy (though there's really no basis for thinking it is conscious )
3. The LHC will test theories that differ on the number of dimensions we live in - the four we know about (3 space dimensions and one time or N/S, E/W and your heightmap for cartographers) or whether there are another 6 or even seven, and whether they are small or large.
4. It may start to shed light on how the universe began and how it may end, and also whether there are other universes.

These are ordered in degrees of speculation. The first we should definitely answer. The last is highly unlikely to be any more than a hint, if we get that much.

But of course, this doesn't answer your question. Neither of those things is likely to immediately lead to any new technologies that will improve your life. Technologies tend to come when we put research into a field where the theory is already known. Fusion has been understood theoretically for about 60 years, but we'll only get our first working fusion plant in 15 years or so. However the theoretical understanding of fusion came from particle physics experiments - and no-one knew when they started those experiments that fusion might come out the other end. The purpose of these experiments is to find out how the universe works. When we peel back another layer, sometimes we find something that can be turned to our own use, sometimes we don't. The point is that in particle physics, unlike many other sciences, we don't know the underlying theory until we look, so we can't say what use the discoveries may have until they have been made.

That said, the field has a pretty good track record. The straightforward results of the work are things like lasers, tvs, radiotherapy and so on. None of these would exist if we had not researched atomic and subatomic physics.

However more important perhaps are the spin off technologies. The LHC has funneled a huge amount of money into brand new research into superconductors, electronics, seismology, solid state physics and (of course) IT. All of the developments that have been made for the collider will be applied in the rest of the world. Without the collider, much of this research could not be done because it would be way too risky for a company to invest that amount of its own capital into R&D that may not work.

Past examples of spin offs are everywhere, but the most obvious is the Web. That was put in place so that the data from the previous collider at CERN could be shared between the international collaboration of scientists working on this. The LHC has a similar challenge - there will be more data produced than ever before and a computer infrastructure needs to be set up to deal with it, and to handle the processing tasks on this data sample. That requires a supercomputer and we've built something called the Grid (yes, we're no good at names) - a supercomputer that spans the globe that consists of networked computers in universities in countries on every continent. You can submit a job to the Grid and it will use the processing power of computers right across the Grid to do the job. It's the largest distributed computer resource in the world and will eventually be made available to everyone, just like the internet.

Hope that answers that question! Wow, that got a little longer than intended....