Part of OnPhilanthropy, an industry newsletter by published by CauseWired Communications. The job listings are free to job seekers. Excellent listing of nonprofit jobs.
Run by ExecSearches which recruits for fundraising, mid-level and executive professionals in the non-profit, education, healthcare and government sectors.
Not specific to the nonprofit sector, but many nonprofits advertise job openings on Craigslist simply because it reaches a lot of people in a specific city who might be interested in nonprofit jobs. Check your city's site under "jobs," "nonprofit sector."