The Escape from Illustration Island blog is a terrific example. Thomas James spends a lot of energy on amassing useful tips of all sorts for artists and illustrators. It's indeed a gold mine.
Here are a few items that I find particularly useful:
What do you wish you knew when you started? Read the comments, where artists (like me) offer hard-won wisdom
68 Useful and Inspiring illustration resources - tons of links here!
How to work with an illustrator, over on Thomas' own site
So if you are a freelance artist, or you know one, or someone you know is considering getting into the field (perhaps after they graduate), send them over. These are the types of resources that artists need in order to run their business and not feel like they are selling out or being taken advantage of. Thanks Thomas!