Originally Posted by
monroeski
Lava, like water, spawns from a source block, so once you find that it's just a matter of waiting for the slooooow flow to disappear.
However, unlike water, you can't create new lava source blocks; You're basically stuck with what you find. With water, all you have to do is make a 3x1 trough with source blocks on each end and the middle block becomes an infinitely renewable source of source blocks. So, once you find a source in lava, you've killed that individual flow; water can be harder to deal with since there could be sources near each other endlessly generating a new one but you can't really visually tell which is which.
Aw hell, that reminds me that I walked over a hill playing late at night yesterday and most of the ground on the other side wasn't showing up, so I got to see the entire underground network of tunnels with lava and water and such (I mentioned this happening before, as did somebody else I think). I grabbed a great screencap, but forgot to paste it into paint before I shut down. :(