What is the best historical example of conflict between two cultures with differing levels of technology?

A typical example would be the colonization of America by European settlers, Spanish at the beginning, and other nations later. This is also a good example how a lot of sci-fi alien invasion stories (or youtube anti-European animation films) try to make a parallel and fail miserably: The meeting of the two cultures of different levels of technology didn't happen D-Day style (or in the style of the movie Independence Day), with the newcomers jumping out of the ships and opening fire on the natives standing on the shore.

Initially there is usually a period of peaceful coexistence, trade, etc. When later conflicts start to develop (don't forget, over the most of human history war was very common even among groups of the same culture, so conflict will arise sooner or later), it's usually not a total war. In the example of the Americas, in lots of conflicts two or more European powers fought against each other, all having native allies. So it was almost never an "every newcomer combined" versus "every native combined" warfare. Internal conflicts were common on both "sides", if we can even call them "sides", as alliances shifted often.

The events leading to the Meiji restoration is a good example although less dramatic than the Conquista.

Your question is pretty much the theme song of the history of Western imperial expansion. Some places to look might be a general history of imperialism. Also a book I much enjoyed that deals with this topic is James Gump, "The Dust Rose Like Smoke: The Subjugation of the Zulu and the Sioux".

Ethiopia? Although they had help from Russia et al, they successfully defended themselves against the Italians; Some using bows, arrows, and spears.

They weren't so lucky during the second war.

http://en.wikipedia.org/wiki/Military_history_of_Ethiopia

I would consider the Mongol empire to be an example of this, depending on your definition of technology. Massed horseback archers using powerful composite bows wasn't anything that most opponents of the Mongols were ready for or knew how to handle.

You could also make a similar case for the English longbow vs. the French cavalry at the battle of Agincourt

The British conquest of Australia and subsequent genocide of the Tasmanians (sometimes reckoned to be the only successful genocide in history) springs to mind as a good example.

Or, on a more controversial note, the Western allies vs. Iraq in either of the Gulf wars. It's probably not the kind of thing you're thinking of but it shows what happens when a more technological advanced and supported nation takes on a backwater without even the long separation of time. Iraqi students were educated in the UK, after all, yet the technological gulf (as well as other logistical issues) made it a grotesque version of a turkey shoot.

One such example that springs to mind is Japan and the "Black Ships".

"Black Ships" was a term that applied to western ships arriving in Japan in the 16th and 19th Century. The Portuguese first made contact in 1593, with the establishment of a trade route between Goa and Nagasaki. This is where the term "Black Ships" is thought to originate, as the hulls of these trade ships were tarred.

This contact with the Portuguese lead to the Shimabara Rebellion, which mostly consisted of Catholic peasants and took place in the south west of Japan between 1697 and 1698. This consequently led to the Shogunate implementing an isolationist policy called "Sakoku", whereby trade with foreigners was limited to Dejima island at Nagasaki.

This policy then lasted until the era of the Meiji Restoration (as already mentioned by Sardathrion), which means that Japan could actually fit your scenario twice.

The Spanish invasion of the Aztec Empire, as you mentioned, is one of the best examples. I'd just like to to mention it again, because although the Aztecs eventually fell to the Spanish forces, it wasn't without a stiff fight - indeed, the Spanish probably would have never even gotten a foothold on the continent without some seriously roguish tactics such as the capture of Moctezuma during a diplomatic visit, and the whole fact that they were viewed as gods at first.

They had grown wildly different military tactics and technology, but I'd not say either was inferior to the others. Had the Aztec and other Mesoamericans taken an initially hostile view of the Spanish, they would have been kicked off the continent in bloody fashion. The obsidian-studded macuahuitl was sharpened finer than than steel could be, and could cleave the head off a horse in a single stroke. The marshy ground was horrid for the armored Spaniards, whose guns took time to load and relatively large amounts of supplies to use and maintain, making them only very effective in pitched battles or sieges. The atlatl was deadly because of the sheer weight behind the point - it could and did pierce amour.

I'm not going to keep going, but look into it. It could easily be that without the belief that white man was a god, the Aztec empire would have stood hundreds more years, and the lack of gold-funded power that the Spanish had would have severely affected European politics.

The Anglo-Zulu war comes to mind.

The story of the (fictional) movie Zulu (from 1964) happens during this war, showing the advantage of fighting spears with guns.