If you're reeeeeally careful, you can get 2 more Analog inouts (only!), A6/A7, by adding wires to ATMega328 pins 19 & 22.
"In the TQFP and QFN/MLF package, ADC7:6 serve as analog inputs to the A/D converter.
These pins are powered from the analog supply and serve as 10-bit ADC channels."
Not sure what you'd have to do software wise to access those.