Digital Artist
A new UK based digital arts magazine which has evolved from the old Painter Magazine to incorporate more software programs. Covers a wider spectrum of genres than ImagineFX. I get both.
Worth1000.com
The only image manipulation contest site you'll ever need. Has a great community and is a wonderful place to pick up advice, tips and criticism. Here's a direct link to my stats page on Worth1000.
ImagineFX
A wonderful print magazine printed in the UK. Always full of tutorials, tips and inspiration. If you are at all interested in fantasy or science fiction digital art you should check it out.
2D Artist
A great magazine devoted to sci-fi and fantasy digital art that's distributed in PDF form online. Low resolution copies of older magazines are available for free from their site.
MorgueFile
A wonderful site for free high quality, high resolution stock photography. Most of the stuff on there can be used freely - usually requiring nothing more than acknowledging the photographer and sometimes they like to see how their photos have been used.
DeviantArt
Huge, diverse online art community. Here's my page.
Lulu.com
An excellent print-on-demand service which I used once to produce a full colour 196 page book for ShackTactical, and am certain to use again.
CGpad.org
Another great online art community. There is some inspiring work on display there as well as some useful digital art tutorials.
CG Society
Great digital art site. Has a very active forum, showcasing some amazing talent.
The Gatehouse
This website has a great collection of Steampunk images... worth adding to your favourites if you like that stuff.