Copyblogger is, hands-down, one of the best blogs on the web related to copywriting and content marketing.
Their main site, www.copyblogger.com, allows you to create an account for ebooks and other resources. The main blog - the really good content - is located here.
In addition to their articles, there are eBooks, Seminars, and Webinars, and Forums available - some for free, some with paid membership.
Though the blog covers copywriting, much of the content is geared towards web masters and towards online marketing and sales conversions.
Amongst the topics regularly covered on CopyBlogger are content marketing, copywriting, SEO copywriting, email marketing, keyword research,landing pages, and internet marketing.
Highly recommended if you're into copywriting, content marketing, web development, new media, or online sales.