If any additional currency should be added is JPN.
The JPN exchanges have no trading fees, so much of the volume is presumably not "real".
I can't keep on adding every little currency that people ask for, or I'll run out of screen space.
Thanks a lot for tweaking the charts to improve the consistency of the numbers contained therein (referring to cleaning up the Euro depictions) and thanks for considering various proposals posters have been making.
Recently, I was also coming to the conclusion that JPN would be important in the near future because of the high volume of BTC trades; however, I had not realized about the no fee situation, which is definitely going to exponentially skew volume upwards and encourage high frequency bot trading and possibly even fake volume, as you mentioned.
Nonetheless, it appears that JPN is going to remain an interesting currency to watch in the near future because of the various recent bitcoin friendly developments, including three major banks investing into their main exchange (bitflyer) and also some of the bitcoin friendly legislation.