I just finished reading this excellent book on InkScape and I think it is an excellent resource for those who want to design graphics for their web application using InkScape and don't have access to commercial tools like Adobe Illustrator.
Link : http://www.amazon.com/Inkscape-0-48-Essentials-Web-Designers/dp/184951268X/ref=sr_1_1?ie=UTF8&s=books&qid=1296398005&sr=8-1