Pin 1, Pin 2, Pin 5, Pin 6, Pin 7 not connected anywhere
this is a big "don't do that" for low power consumption. Even though it is common practice in arduino software, it is a bad idea to leave pins configured as inputs AND not connected to anything; they can easily "float" at non-digital signal levels (or even oscillate), causing unexpectedly high current consumption.
I'd be curious to hear if you actually see any change in consumption JUST by changing the pins to outputs.
And... I usually refrain from commenting on issues of programming style, but THIS is really awful:
_SFR_MEM8(0x30)= 0x03; //disable Brown Out Detector Control Register
_SFR_MEM8(0x35)&=0x83; //PUD disabled, Sleep enabled, Power Down mode
_SFR_MEM8(0x25)=2; //Power reduction timer enable
Those registers, and their bits, are defined for you symbolically in avr/io.h (etc), which is included for you by the arduino system (the same place that _SFR_MEM8() is defined.) You should use them. (in fact, those registers are all defined as "_SFR_IO8(x)", which is not the same as _SFR_MEM8(), so perhaps those lines are not doing what you think they are doing AT ALL!)