Yeah, I thought magma worked like water (you can make a 4x1 pool of water that's basically an infinite source of water), but magma doesn't do that. Pools seem infinite because they are so deep.
See, when you put water or magma in a bucket, you have to pick up a magma or water unit (a spring), not something that flows out of that. But for some reason, when you remove water from a pool, and the other water around it fills it up, that becomes a new spring. That does not work with magma (believe me, I've tried), possibly because that would create a way too easy access to obsidian. And, I guess, lava in general.
For some reason, the infinite water trick doesn't work in the middle of the sea, picking up water there seems to leave a block that has four other blocks of water flowing into it, giving a kind of whirlpool-effect. The infinite water thing also means that you can take a small pool, fill it with thousands and thousands of liters of water (1 block = 1x1x1 meter = 1000 liters), and still have it stay as big as it is, due to water never being allowed to go higher than itself. The same, sadly, goes for magma, making magma misplacing such a hassle, since you have to go all the way back underground to find magma again if you misplace it atop of a full lava pool.
Fancy water effects are difficult to make, but I'm working on a nice-looking waterfall down the side of a tower. Also going to finish up my sword when I bother to start moving lava again. I also want to make an awesome railroad, but it takes so much steel.