I've used Domino's dots before with good success when I use to bottle.
One cube per 12oz bottle gave me good carbonation, if I had to guess maybe 2-2.5 vols.
Yes bucknut, I'll have to admit that's probably the simplest and cheapest bottle carb solution. But it's one-size-fits-all. What do I do when I want to bottle some English Bitter at 1.7 volumes of CO2 or Dunkelwiezen at 3.2? Also how do I know those sugar cubes are reasonably bacteria free?
Well actually if 1 cube in 12oz gives 2.25 vol, then 1 cube in a 16oz bottle would be 1.7 vol. 2 cubes in a 16oz bottle would be 3.4vol.