Andrew Goodman offers a free 40 page guide to Google AdWords.
Dave Winer and Paul Graham published articles about how complexity and corporate thinking increase the cost of doing business and stifle innovation. Worth reading both of them.
Michael Gray offers great tips on how to do SEO for video content, and recently published a guest article by Gab Goldenberg on how to be creative.
Weip offers some great link building tips.
Vanessa Fox offers a ton of great Geotargeting tips, and highlighted Nathan Buggia's great post on issues associated with URL referrer tracking.
Allegedly searching stimulates the brain. Smashing Magazine offers tips on search box design. And Yahoo! is testing ways to make search ads pop by using graphics.
Paypal modernized allowance by making it automated, and giving you the option to send extra on demand.