I'm going to be finishing off a few more categories of Hugo winners in the next week or two so I will start with the two winners for Fan Artist who I have not mentioned yet.
Something I've been struck by as I went through this is how difficult it has been to find samples of most of the fan artists' work on the Internet. Even with the recent ones I have had trouble finding anything beyond a random sampling, the occasional fanzine cover, and a mention as a con attendee.
2003 and 2005 Hugo Winner for Best Fan Artist
There are multiple artists by the name of Sue Mason which gave me a bit more trouble than usual in hunting her down. I did find cartoons drawn for different sources but she maintains a website for selling her custom pyrographic, wood burning, art. There's several interesting samples of her work at the site and it is worth taking a look at.
2004, 2006, and 2007 Hugo Winner for Best Fan Artist
There is a very extensive gallery of Wu's work online. In addition to that there is, unlike the vast majority of fan artist, a book of his art available.