A few links on ipv6 subnet calculators from one topic on Linkdin:
http://www.ipv6calculator.net/
http://www.addictivetips.com/windows-tips/
http://bitace.com/ipv6calc/
http://www.ipv6book.ca/allocation.html
http://sourceforge.net/projects/ipcalculator/
http://depierri.com/ipvi/index-en.html
http://www.subnetonline.com/pages/subnet-calculators/ipv6-subnet-calculator.php
http://grox.net/utils/ipv6.php
http://www.wxnz.net/ipv6-subnet-calculator/
http://www.gho.no/online-web-ipv4-and-ipv6-ip-subnet-calculator/
Just table of netmask ipv6:
http://bind.com/?path=netmasks6
Just decode from ipv6 address
http://v6decode.com/