Provide Test Expertise to Test Group

The test manager should provide some test expertise to the test group. This expertise comes in a variety of forms:

Ability to discuss, mentor, and/or train current employees on general testing techniques.
Ability to look forward to the products in development and planned for development, to foresee what new expertise and training is needed by the group.
Ability to hire people based on current and future testing needs.

Note that this does not mean the test manager has to provide specific low-level tests for the product. A test lead's job is developing tests, not the test manager. As a test manager, you provide leverage to all the testers and to corporate management. You need to define for yourself the difference between mentoring and doing other people's work.