Electoral college is the only thing that keeps smaller states relevant to national, two-party politics. While it's far from a perfect system, no one outside of Colorado would care what the 5.1 Million Coloradans think about anything if it weren't for the fact that whoever wins at least 51% of our votes gets the power of all of nine of our Electoral College votes.
If “popular vote” advocates had their way, the only places that would matter to politicians on a national scale would be the population centers – Southern California and the East Coast
Sorry Rust-Belt factory workers. Sorry ranchers. Sorry hunters, fishers, hikers, motorcyclists. Sorry fly-over states. Unless you live in a large population center where politicos deem worthy of spending their time, your concerns no longer matter and will dictated by those who probably have never even seen your state.
No national politician would waste their time traveling through Colorado, Ohio, or Iowa unless they knew that they needed to get enough of their supporters to turn out to tip the whole state in their favor. Otherwise they would spend all of their time pandering to the coasts and never even think about the states that have a total population lower than the particular metropolis they're fundraising in that day.
Of course, this results in some pandering the other way, too. The Farm Bill wouldn't be nearly as much of a mess if Iowa weren't a swing state. No one would care about National Forest logging rules if Colorado weren't a swing state. This can go either way depending on how and if these thing affect? your daily life, but it does bring otherwise dull issues to the national spotlight from time to time.
I think the Framers knew what they were doing when they decided on the Electoral College system of presidential politics – giving “smaller” states a little more leverage against their “big” neighbors in a two-party system. This does screw up any chances of a viable third party, but that's an issues for another day...
Sorry for the rant.
Good FAQ on the Electoral College here.