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:
BTW, the font used to write "Debian" in the logo is a payware font called Poppl Laudatio Condensed.
The i-Dot has been manually replaced by a red diamond.
Julien Blache annotated (http://lists.debian.org/debian-devel/2005/07/msg00262.html) that the text has been condensed horizontally and stretched vertically.
There is also a resemmbled free font at http://www.flyerstarter.com/Free-Fonts/L/Laudatio-C.html.