From Wikipedia, the free encyclopedia
### faves doodlebug
http://doodlebug.desktopcreatures.com/members/mertyperty/56038
http://doodlebug.desktopcreatures.com/members/sethrocks/79229
http://doodlebug.desktopcreatures.com/members/meryl
http://doodlebug.desktopcreatures.com/members/Pesare/69046
http://doodlebug.desktopcreatures.com/members/Serg.S/80677#doodle
http://doodlebug.desktopcreatures.com/members/Dante/83555#doodle
http://artpad.art.com/artpad/painter/
### hierarchy
* http://www.qcodo.com/forums/topic.php/293/1//?strSearch=hierarchy
* http://www.yafla.com/papers/sqlhierarchies/sqlhierarchies.htm
* http://www.developersdex.com/gurus/articles/112.asp ;; nested set
### rails acts as tree
* http://www.railsforum.com/viewtopic.php?id=1560
* http://www.intertwingly.net/blog/2005/08/25/Acts-As-Tree
* http://wiki.rubyonrails.com/rails/pages/HowToUseActsAsTree
* http://pastebin.com/
### NDFA DFA
* http://www.matasano.com/log/1009/aguri-coolest-data-structure-youve-never-heard-of/
* http://swtch.com/~rsc/regexp/regexp1.html
* http://www.techcrunch.com/2008/01/17/yahoo-implements-openid-massive-win-for-the-project/
###
*http://en.wikipedia.org/wiki/Rock_stacking
*http://en.wikipedia.org/wiki/Cairn
*http://en.wikipedia.org/wiki/Inukshuk
