If life "biggest" doesn't always equal "best".

I would try to find newsletters and blogs relating to your specific marketing strategy. Because "marketing" is a very broad term.

Also this forum is a hell of a resource. Do a search for what you're interested in and go to town.

I know it sounds boring, but I can't tell you how much of my skill-sets I have learned from searching forums and Google.

IMHO that logic is a little faulty.
Only subscribe to those marketers who offer information that you need or interests you. There are so many facets to IM, you'd never be able to focus on your own success if your only criteria about who to follow is list size.

What are you interested in? Building and marketing your own products or affiliate marketing? If you want affiliate marketing, do you want clickbank style(digital products), amazon style (physical products) or CPA?

If all you did was subscribe to big lists without any sense of purpose, you'd be bombarded constantly with information about all these methods and then some. You'd never get anything accomplished.

I want to say the "Internet Marketing Center" list... which used to be owned by Corey Rudl before he passed. It's ran by Derek Gehl now.