Logos can be found on the Debian logo guidelines page at: http://www.debian.org/logos/
The official logos have been selected by vote of the Debian developers in Mid 1999.
They have been created by Raul M. Silva (http://www.silva.com)
Get banners to show your Debian pride at:
Read the Debian Graphics blog here:
[http://io.debian.net/~tar/volkany/ Volkany]  produced very good Debian graphics.
BTW, the font used to write "Debian" in the logo is a commercial paid font http://email@example.com/msg01627.html 0 called Poppl Laudatio Condensed http://www.myfonts.com/fonts/berthold/laudatio-be/condensed/ 1. The i-Dot has been manually replaced by a red diamond. [http://lists.debian.org/debian-devel/2005/07/msg00262.htm Julien Blache annotated that the text has been condensed horizontally and stretched vertically]. The "debian" text can be found in vector format at http://www.debianart.org/cchost/?ccm=/media/files/si0ux/59 5.
There was also a resemmbled free font at http://www.flyerstarter.com/Free-Fonts/L/Laudatio-C.html 4 - a page that still hosts it is at http://www.abstractfonts.com/search/laudatioc 3.