I've been getting Chuck Green's newsletter for a few years, and even though I don't design marketing materials, I've always clicked through to discover his newest do-it-yourself design tips and information.
His site, Ideabook.com is a great resource for information on writing and designing myriad marketing materials. Even though my design experience is minimal (I've created two original publications -- a newsletter and a fundraising postcard), I've always clicked through his monthly newsletter links (most recently I'm a fan of Jumpola Design Links) and visit the site pretty regularly to check out what's new.
Today, Green's newsletter included links to free templates he created for printer manufacturer, Oki; Ledpants.com -- a design studio that, quite honestly, has a pretty whacked out, but interesting, website; and This American Life, where web users can listen to various stories, from documentaries to fiction, produced by WBEZ in Chicago. The variety in the newsletter is great, and it gives you an insight into Green's interests while selling his design expertise.