Inkscape is a wonderful vector graphics program that I have been using to create marketing information for Guinterface and my business in Second Life. I cannot say enough about this package. I'm not a artist by any stretch of the imagination but this package is intuitive enough and powerful enough to make me look like one. Although not as polished as some more "professional" package (read Adobe products here), it manages to combine enough features to make its asking price ... $0 seem very cheap.
Here are some of the things I have done entirely in Inkscape for my businesses: