Digital Art Production:
Frenden: A great artist and source for digital product info, I personally use his Manga Studio Brushes for most projects. His blog is also an invaluable resource for me when picking out new tech.
Blambot: I cannot speak highly enough for this site, every font you see in Underdogs is from his site. The owner/creator Nate is phenomenal, and even has a small guide section for comic lettering.