Down on the Waterfont

Researchers using waves to write on water:

...Their second attempt, however -- developed with Professor Shigeru Naito of Osaka University -- addresses both major flaws by using formulas known as Bessel functions to cut the processing time down to between 15 and 30 seconds and form characters with straight lines. The 30-centimeter deep, kiddie pool-sized device employs 50 generators operating in unison to produce cylindrical waves that behave like pixels, giving it the ability to display the entire roman alphabet as well as a number of kanji characters.

Well, that's nifty.