Chicago-The dot-com shakeout continues unabated. The number of dot-com job cuts increased 19 % in December, compared with November, according to executive search firm Challenger, Grey & Christmas Inc. The last several months have seen countless Internet companies either go belly-up or significantly cut back their payroll. Pets.com is just the latest high-profile Web site to go out of business, and Red Herring Communications announced last week that it was cutting nearly 10% of its workforce. December marked the seventh straight month of increasing online-related job cuts.