ACM
http://acm.timus.ru/
http://www.hsin.hr/coci/
http://www.codechef.com/
http://ace.delos.com/contestgate
http://z-trening.com/index.php
http://61.187.179.132:8080/JudgeOnline/problemlist
Algorithm
http://www.prefield.com/algorithm/index.html
http://www.csie.ntnu.edu.tw/~u91029/index.html
Mathematics
http://www.cut-the-knot.org/
http://gurmeetsingh.wordpress.com/puzzles/
Hiking
http://www1.map.gov.hk/gih3/view/index.jsp
http://www.ofta.gov.hk/zh/ca_bd/country_map/index.html
Blogs
http://www.matrix67.com/blog/
http://vihart.com/
http://zhiqiang.org/blog/
http://mindhacks.cn/
http://cuitianyi.com/
http://mr_riceball.mysinablog.com/index.php
Go
http://bogi_666.myweb.hinet.net/dingshi/dingshi-000.htm
Useful
http://www.online-utility.org/image_converter.jsp?
http://www.codecogs.com/latex/eqneditor.php
