I can't seem to play this game without mods. I just can't. The modding experience is just too awesome.
So far: Dragon block c, buildcraft, industrial craft experimental, treecapitator, minecraft comes alive, ancient warfare, archimedies airships, and not enough items.
Oddly enough, these mods have a crazy good symmetry. It really feels like a good dragon ball experience with the added towns and castles for ancient warfare. Archimedies ships allows me to build oil tankers to take advantage of the underwater oil, and air ships to carry the oil to a main refining base.