Form a task force of former government employees to review federal agency operations and identify wasteful and inefficient practices, then act on their findings. A savings of 10-15% is the minimum result.
Examples: unnecessary cell phones, blackberries or pagers (and their expensive service plans), unnecessary assignment of government vehicles (unless required to perform your work duties), cumbersome regulations, unnecessary paper documentation (do it electronically), maintain an industry-recognized supervisor to subordinate ratio, move workers where the work load is heavy (instead of lay-offs or a partially idle workforce), replace furnishings and equipment only when necessary (not because you have money to spend).
This idea does NOT require any action by Congress.