I took Bill's dense build strategy to an extreme one game (Regent, Small Map, Continents, 80% water) when I found myself all alone on a roughly 60-tile island, which was about 80% jungle. You can squeeze in maybe 6 cities without getting much overlap, but I packed in about fifteen cities on the island by going one on the diagonal or three on the straight when founding my next city, ignoring the fact that I was palcing cities in the middle of the jungle. I built worker after worker, and didn't even bother building more than a warrior in each city. Eventually, the jungle was cleared, and I had pretty decent production out of all the cities. By the time I'd researched the tech to sail the seas, I figured I'd be eons behind in the tech race, but I was even with all the other civs by the time I made contact. My production was almost twice what any of the other civs had at the time, which was evident by the equal tech levels without the benefit of trading. I started building my defensive force and assault force and eventually got a pretty substantial beach head on another land mass (much to the dismay of the millions of innocent French citizens burned to death as I marched over their once proud lands).
The cities on my starting island wouldn't grow past 9 or 10, so as a long term strategy, dense build isn't a great idea, but once I'd established myself on the other land mass, I shipped a whole bunch of workers over to one of my new cities, got it up to size 12 (no foreign nationals) and disbanded my capitol, so I could jump the palace to the new land mass while I kept the forbidden palace in the middle of the initial island. I eventually disbanded about half of my initial cities. This provided me with enough settlers to found new cities over the ashes of the razed cities on the new land mass as my armies continued to march over the French, German and English lands.
The early dense build made my civ almost unstopable even with the less than optimal starting location. I was like a man among boys when I first made contact with the other civs.
Reg