Here is the new shield by BlueberryDe.com its a 24CH Analog Expander using 3 CD4051 Mux IC’s and a MCP2008 for i2C communications to control the Mux chips! The entire addition of 24 Analog inputs comes while only using 3 of the onboard Analog Pins! A3, A4 and A5, also A4 and A5 can be used for other i2C hardware at the same time! The Board has been designed with reliability and quality in mind. a 2mm thick PCB, SMT components mounted on the underside and long legged extender headers. These long headers allow the Shield to be stacked with other shields if desired. We also included an i2C Address Header to control the A0,1 and 2 pins of the MCP2008 chip allowing more i2C hardware to be used without issues. We will post the schematic soon, for now you can view the product, purchase it and download the library we wrote to make using it easy from here http://blueberryde.com/shop/24-channel-analog-expander-shield/
Once you setup the library there is an Example included. The library allows a simple method of checking any of the extra 24 Analog pins through the use of something like this int val = mux.AXread(23); This would read the value of AX23 and return its value to the variable val.