Add attributions.

README.md

@@ -7,8 +7,22 @@
     \ \____\\ \____/ \ \____/\ \____\
      \/____/ \/___/   \/___/  \/____/
 
-See <http://square.github.com/cube>.
+See <http://square.github.com/cube> for an introduction.
+See <http://github.com/square/cube/wiki> for documentation.
+
+## Thank You
+
+Cube is built with the following open-source systems and libraries:
+
+* [D3.js](http://mbostock.github.com/d3/)
+* [MongoDB](http://www.mongodb.org/)
+* [node-mongodb-native](/christkv/node-mongodb-native)
+* [Node.js](http://nodejs.org/)
+* [PEG.js](http://pegjs.majda.cz/)
+* [Vows](http://vowsjs.org/)
+* [websocket-client](/pgriess/node-websocket-client)
+* [websocket-server](/miksago/node-websocket-server)
 
 ## Contributing
 
-We'd love for you to participate in the development of Cube. Before we can accept your pull request, please sign our [Individual Contributor License Agreement](https://spreadsheets.google.com/spreadsheet/viewform?formkey=dDViT2xzUHAwRkI3X3k5Z0lQM091OGc6MQ&ndplr=1). It's a short form that covers our bases and makes sure you're eligible to contribute. Thanks!
+We'd love for you to participate in the development of Cube. Before we can accept your pull request, please sign our [Individual Contributor License Agreement](https://spreadsheets.google.com/spreadsheet/viewform?formkey=dDViT2xzUHAwRkI3X3k5Z0lQM091OGc6MQ&ndplr=1). It's a short form that covers our bases and makes sure you're eligible to contribute. Thank you!