With infinite lava comes infinite obsidian... So I had to construct an obsidian generator
Here is the general idea of it:
1) Create the standard plus. Dig down in the middle and place a sign as in the picture.
2) Fill with lava.
3) Cover the lava but leave one block open in the middle.
4) Put piston on top of hole, and invert the input form a button so it's always extended unless the button is pressed.
5) Put water on top of piston.
6) Standing at the bottom of the hole we dug down in the first step you should now see this:
7) Now it's simply the matter of pressing the button and the lava should be converted to obsidian (or cobblestone in my case as I'm still on 1.8 ).
There is however a problem with this generator and that is that it's highly likely to eat your obsidian when it drops as there is so much lava around. One could probably fix this by constructing a feeding mechanism so you instead of mining it directly push it away with pistons and mine it somewhere away from the lava.
Edit: But it just occurred to me that you can't push obsidian with pistons so that solution is in the trash