Advertising World
The ultimate marketing communications directory from the University of Texas department of advertising. Hundreds of sites.

Adbusters
Not industry sanctioned. Say the Adbusters: "We will take on the archetypal mind polluters - Marlboro, Budweiser, Benetton, Coke, McDonald's, Calvin Klein - and beat them at their own game."

American Association of Advertising Agencies
Primarily a membership organization without a whole lot of resources on the site. A look at their member list can be helpful for quickly locating agency contacts.

Audit Board of Circulations
A nonprofit association of advertisers, advertising agencies, and publishers all working to keep magazines and Web sites honest when it comes to reporting circulation numbers. Ordering reports via snail mail costs a few dollars - most reports aren't available on the Web.

CyberAtlas
Chock full o' Web advertising argot - so you'll finally learn the difference between "impressions" and "gross exposures." A great place to find news stories on Web advertising, stats, demographics, advertising/marketing links, and contacts for market researchers.

Magazinedata
Set your sights on your next market. This list includes a directory of media kits and a database of advertising data for top Web sites. With the notable exception of Wired, the data is extensive.

Marketing Lists on the Internet
You can usually sign up for these discussion lists with one email. Marcom consultant Kim M. Bayne has helpfully provided a description of mailing lists of every stripe and hue - and she notes whether they're moderated or not. Come to think of it, an unmoderated marketing list probably wouldn't be much fun, due to heavy spam potential.

Media Central - Advertising and Promotions News
Cowles Business Media, which runs a number of trade magazines, collects the day's marketing news and commentary from its different publications. They've also organized a directory of agencies on the Web.

Online Advertising Discussion List
More than a thousand members subscribe to this free mailer. The discussion is usually pretty interesting. Discuss online advertising on the mailing list, or search the archive of messages.