CEO Express
Business oriented portal. Straightforward interface. Relevant links. Premium content available to paid members. Otherwise free.

Many Worlds
A relevance engine with links to many strategic articles on product innovation and business strategy. Woefully inadequate when it comes to marketing content however. The relevance engine is neat however and worth exploring. Membership is free.

B|NET
From the makers of C|NET. All things business. Membership is free.