I have to say that I tend to agree with Eric's last post. I would be less likely to agree that our times are more enlightened, especially as to property (this is another debate altogether). As wonderful as libertarians like Stanya think think things would be without eminent domain, it was provided for by the takings clause. Historically, there probably has never been a functional understanding of property more libertarian than in the US. That being said, you own your property only with the government's consent or protection. So, a libertarian ideal, while economically good, can only be realized by force or by political persuasion, meaning requiring the government through our political processes to protect property. Therefore, it is probably wrong to say you have a right to your property beyond which you cannot enforce it yourself. It would be good if government functioned on the proposition that there is a natural right to property, but natural rights don't enforce themselves.
The definition of 'public use' in precedent, like much else, expanded over time. Legitimate definitions might be the obvious, government buildings, schools, roads, etc. Eventually public use came to include common carriers such as railroads, so that if it was something available for all the public to use, it qualified. These have always been pretty uncontroversial. Recent precedent, though, has changed public use to public benefit, clearly a huge expansion of qualifying exuses to use eminent domain. The important case slips my mind at the moment, I believe it was in the early sixties, began this expansion of what was a public use. A bad example to me was Hawaii Housing Authority v. Midkiff in 1984, thus pre-Scalia and Thomas. O'Connor wrote the opinion (though, she did dissent in Kelo) saying Hawaii could transfer a bunch of property from lessors to lessees because so much property was concentrated in so few owners' hands. The claim was this caused property prices to be extraordinarily high, and difficult to acquire. The court voted 8-0!!!! So that, now, as I mentioned, if there is any conceivable public benefit (tax revenue, aesthetic value might even qualify), the taking will be ok'd by the courts. The only caveat was Justice Kennedy's concurrence (since he was the fifth vote) suggesting the gain must be rational and substantial to some minimal extent.
Finally, to scare you Stanya, State and local governments may take property or regulate it so as to destroy some of its value as long as there is a legitimate police power reason without compensation as you and I talked about with zoning laws.
