OK, Nathan, let me first make a wisecrack about your definition of what is an extremist idea. If you apply it literally, the single-payer system of health care falls under this definition, don't you think? It does change the fundamentals of how health care is provided in this country, and could have led to violence if it were adapted because a majority of the country is so much against it.
Now about the Tenth Amendment, which I understand very differently from you. You write that this amendment allows states to pass any laws that do not contradict the federal laws. If this were the case it would have been a non-issue from very beginning. I think, however, that the meaning of this amendment is much less trivial than your post suggests. My understanding is that it forbids the federal government to make laws in the areas outside of those that are defined by Constitution. The practical application of this amendment depends on interpretation of several Constitutional clauses, mostly the Commerce Clause.
Some of the examples that you have used to make your point are, in my opinion, out of place. For instance, funding of research by federal government falls very well under the Welfare clause of the Constitution, and I do not remember any states disputing it. So let's focus on things more relevant to the issue under discussion. Minimum wage law, which, in my opinion, is a bad law, was indeed challenged under the 10th Amendment, but I do not think it is really a 10th Amendment issue or at least not in its traditional understanding as state versus federal government dichotomy. However, this is also topic for a separate debate.
Now let's talk about the Tenth Amendment itself, which has more interesting and controversial history than your post implies. In its heart is the dispute over separation of power between state and the federal governments, which is as old as the Constitution itself. Respectively, the tenthers movement is of about the same age and was not created by the Tea Party. At various times throughout the history, this movement moved to the forefront of the public consciousness or receded to the subconsciousness of the nation, depending on the expansion or shrinkage of the powers of the Federal government. It is hard to see this movement as extremist given that the first Tenther was none else but Thomas Jefferson. He invoked it in his dispute with Alexander Hamilton regrading the 1st Bank of the USA, and while Washington took Hamilton's side, the 10th amendment continued to be considered an important part of the Constitution. During the years before the Civil War, many states, not just Southern ones, tried to use it to block Federal legislation, which they deemed as violating their rights. However, the dispute over the "tariff of abomination" and the nullification crisis of 1832, which you mentioned in your post, was not really a 10th amendment issue. South Carolinians saw that tariff as an attempt by the industrial North to improve their economic situation at the expense of agricultural South and their actions was a just attempt to save livelihood of the state's citizens.
Civil War and the victory of the North made, of course, 10th amendment dormant for quite a long time, but eventually it did make a comeback with 1883 Supreme Court decision striking down the the Civil Rights Act of 1875. The 20th century, and in particularly, the New Deal policies of Roosevelt, weakened this amendment again, however, it was used in several Supreme Court cases as a basis for litigation, sometimes successfully, during entire of the 20th century.
Thus, I would argue that attempts to limit the power of the Federal government with the help of 10th amendment is a long standing tradition in the ever changing political discourse of the country as it tries to balance and re-balance the rights of the federal government, state government and the individual. In my opinion it is a very useful tool to keep the government in check, because any government has the tendency to expand its power further and further unless it's not prevented from doing so by the laws and people willing to invoke them. In 1985 ruling, Supreme Court delegated to the Congress the power to limit its own power through the democratic process shifting the problem of the power balance from legal to political realm. I do not completely agree with it, but as it stands now, it puts a great responsibility on the citizenry to make sure that their representative in the Congress vote only for those laws that give Federal Government as much power as people are willing to give to it. In this situation the 10th amendment becomes a useful political tool to limit the growth of the Government. So, in my opinion, the Thenters are not extremists, they continue a long tradition that began with Jefferson, and which helped the people of this country to remain as relatively free as they are now. Because any expansion of the Power of the Government means narrowing of people's freedom.
Just one additional thought. The Tenth amendement issue might appear to be a specifically Southern issue, which is not too surprising given that after the loss in the war, the South was occupied by the Northern troops and was deprived of their simplest liberties. I also think it is wrong to demonize the 10th amendement because the South used to it to protect their rights to keep slaves. After all, human laws as well as natural laws can be used for good and for evil, but we do not demonize Einstein's mass-energy relation because it lies in the foundation of the atomic bomb, do we?