Blockchain is a great toolset for voting. NXT had one of the earliest voting systems that I'm aware of and its quite robust.
The problem that concerns me is the validity of voting in the first place. When it comes to traditional politics, I say it is really just violence - two wolves and a sheep deciding what's for dinner.
Now, a more relevant and peaceful way would certainly need the power and transparency of the blockchain too - that would be for situations, say roads, or public works. We could end eminent domain by using an auction system of votes to determine the best places to put stuff and then we could use very similar tech to fund and maintain these projects.
Will have to look around for NXT, thx for the share!
As it goes for the validity there is nothing much that we can do : we have to chose from the few, we can't change that or at least easily. We can try to ensure that at least voting process is fair