Where is the best places to find faculty job postings in physics?

If you're a member of the American Physical Society (APS), I would recommend looking there first (http://www.aps.org/careers/employment/index.cfm). Many universities will post here, as it's the official representative of physicists in the United States.

In addition, I recommend looking at university department webpages. If there is a certain region or state you'd like to work in, narrow your search to universities there.

Though not specific to physics, I think The Chronicle of Higher Education job search site seems to cover several fields fairly well, and I looked there often when I was searching. In fact, narrowing down the search at the Chronicle job site for physics faculty/research positions in the US yields several relevant hits.

For completeness, here are a few other job sites that I've used that you may find useful:

• AcademicKeys, with a listing of current physics openings in the US here.
• HigherEdJobs, with a listing of current physics openings in the US here.

One of the best sites for job seekers is the Academic Jobs Wiki. Not only does it have postings, but people also update whether they've gotten past the first round, second round, phone or physical interviews, and other status changes including searches being shut down by provosts, etc.. This lets you know whether to keep hoping or to give up.

http://academicjobs.wikia.com/wiki/PhysicsPositions

There are academic job wikis for other fields, I've only posted the physics one above.

Update 2019.7: please note that in the four years since posting this, I’ve heard several reports of people gaming the wiki jobs system: reporting a position closed when it isn’t, reporting a different direction to the search to throw off competitors, etc. As with all crowdsourced systems, use with some caution and only as a supplement to other sources of information.