The 2D Toolkit demos use some freely available artwork from these following sources.

Folk/Londrina font designed by Marcelo Magalhães Pereira
http://www.marcelomagalhaes.net/59823/546166/-works/londrina-typeface
http://www.myfonts.com/fonts/tipos-pereira/londrina/

"Planet Cute" art by Daniel Cook (Lostgarden.com)
Some of the sprites (Brown Block, Chest Closed, Stone Block, Rock) are from the Planet Cute collection by Daniel Cook from this website:
http://www.lostgarden.com/2007/05/dancs-miraculously-flexible-game.html

Explosion texture generated from:
http://www.nuvorm.nl/?p=1

Commodore 64 font by Devin Cook.
http://www.dafont.com/commodore-64.font

Old Sans Black font by Manfred Klein
http://manfred-klein.ina-mar.com/

MV Platformer Male by MoikMellah (CC0)
http://opengameart.org/content/mv-platformer-male-32x64

Nunito font by Vernon Adams (SIL Open Font License)
http://www.google.com/fonts/specimen/Nunito
