Dumb question!

[YinYin]

Sure! What I was trying to refer to was the bonding between the individual water molecules. Yes, the density of cool liquid water is higher than that of ice, however, the bonding in its completeness is much lower.

I knew you were comparing to the solid ... I just couldn't believe you talking and explaining water (even pulling out the molecule structure without actually using it) but never mentioning why it's awesome. So I had to say No :p

If you walk over ice the weight of your body (pressure) will melt the top layer of it, forming a small liquid film that will make you slide (otherwise you would be able to walk on ice as if it were concrete).

That's actually not the full explanation. Ice is still slippery, even when it's ridiculously cold (< -20°C). According to your phase diagram, it should be impossible to go ice-skating in Scandinavia. Surface science predicts that the topmost monolayers are less-bonded to the solid but still not fully liquid-ish.

I wasn't talking about ice skating really, because that also involves friction and thus heat.
Not to mention that blades can have a ridiculously small standing surface, which increases the pressure of your body weight immensely. (can't find a figure for the blades surface area right now - we should calculate this through some time though!)
So I'd say pressure and friction heat should always suffice to liquidise some layers of ice for gliding effects under earthly conditions (>-100 °C). I only think that the rate this happens at (or the size of the already liquid layer) gets smaller with temperature.

Also your uncited predictions are still linked to the special polar Hydrogen bonds and thus abnormal density at 4 °C.
And I prefer facts over predictions.

This is fun.