Mugen Power has just built a battery for the Note 2. So, you take the 3100mAh battery, which Tom has stated his would probably last 16 hours (he uses it for about 8 hours a day and has 50% left), and then you more than double that to 6400mAh
32 hours of battery life. You could go away for the weekend, use it semi-judiciously, and still come home before it died out.
Impressive.
And for $100 you not only get a kick-ass battery, it also comes with NFC. Sounds like a great Christmas gift for some folk I know with a Note 2 (as it ships on December 21).