I find the easiest way to photograph my artwork to publish on the web is to simply shot a digital image of my work outside in the shade. Remember to hold the camera steady, turn off the flash, shot straight on, and make sure you are shooting in a solid shaded area (no dappled light).
Here are some great articles that explain the process in more detail...
"How to Photograph Art" by Dallas Art Revues
"Digital Abracadabra: Posting Your Art on the Web" by Scott Burkett from Wet Canvas
"How to Successfully Photograph Your Own Artwork" by Sylvia White