So, my earth-mage PC wanted to make a Divination focus, but wasn't coming up with any ideas beyond the very basic "tracking spell" level. I threw some ideas around and we came up with a
cleromancy focus; basically, a large sand table with a silver ring containing the whole thing, a couple hundred hand-carved stone dice (in the platonic solids, carved with numbers and runes, in about 50 different types of stone), and a variety of dice cups. The procedure would be along the lines of drawing lines in the sand (days, weeks, months, for time, state borders for long distance location, etc) and then throwing the dice to see where they land and with what numbers.
So, that got me wondering: this is very much an earth-mage's focus, with the sand, and the carved rocks and metals and whatnot. What other ideas have people come up with for their divination foci, especially for the other elements?