Most of these groups have monthly meetings:
Seattle Direct Marketing Association
Puget Sound Chapter of the American Marketing Association
WSA, formerly the Washington Software Association, sometimes has marketing-related talks.
MIT Forum of Western Washington sometimes has marketing-related talks.
PRSA chapter of Western Washington
Puget Sound Chapter of SIG-CHI: focuses on usablity of web sites, often a key to retaining visitors.
To suggest additional resources about marketing in Seattle, contact us.

Montlake Bridge, Seattle