A Visualization Methodlogy for Characterization of Network Scans, Chris Muelder, Kwan-Liu Ma, and Tony Bartoletti, to appear in Proceedings of VizSEC? 2005, October 26, 2005. http://www.cs.ucdavis.edu/~ma/papers/scanvis.pdf
Interactive Visualization for Network and Port Scan Detection, Chris Muelder, Kwan-Liu Ma, and Tony Bartoletti, to appear in Proceedings of RAID 2005, September7-9, 2005. http://www.cs.ucdavis.edu/~ma/papers/raid05.pdf
Books
Information Visualization: Perception for Design By Colin Ware Published by Morgan Kaufmann, 2004 ISBN 1558608192 (alternate, search), 9781558608191 486 pages
Information Graphics: A Comprehensive Illustrated Reference By Robert L. Harris Published by Oxford University Press US, 1999 ISBN 0195135326 (alternate, search), 9780195135329 448 pages
http://www.rumint.org/ - rumint (room-int) is an open source network and security visualization tool (pcap)
http://www.secviz.org/node/89 - DAVIX, a live CD for data analysis and visualization, brings the most important free tools for data processing and visualization to your desk.