I actually thought a little about this, kikashi said that a natural ability to use two elements was called a Kekkei Genkai.. I started thinking about this in a general term by associating a few of the known Kekkei Genkai with various elements.
As posted we already know the Wood Element is (earth+water) and the Ice Element is (water+wind). Both of those are types of Kekkei Genkai, but he also mentioned that the Uchiha's are naturally able to use fire techniques, so for the Uchiha Kekkei Genkai we have (fire+???). If we disect what we know about them, their clan symbol is the fan (which is said to "Fan the flames of the Uchiha clan"). Also, they are supposed to be related to the Hyuga clan. Neji as we all know, has the Air Palm technique, which suggests he's has a wind element. So if the Uchiha are related to the Hyuga and the fan symbol suggests more to the clan's Kekkei Genkai than previously thought, the Uchiha clan is probably a (fire+wind) element. Another one I think I've got figured out is the "missing kazekage" (the one sasori controlled as a puppet). His Kekkei Genkai technique and Chiyo gave that away for me. She stated the Iron Sand technique worked because (iirc) he used magnetic waves to control it's movement. If that's so, he would need to be a lightning element type to create the magnetic waves and earth element type to manipulate the iron sand. So he would be (lightning+earth).
So best I got to add is:
Uchiha (fire+wind)
Old Kazekage (lightning+earth)
Hyuga (wind+???)