I was laid off in March. My main source was LinkedIn Jobs . If you have a large network of LinkedIn connections you will see who you are connected to at the company of the posted job on LinkedIn Jobs. This allows you to have a lead at that company to at least reach out to them about the position.
The below may be common knowledge to many, but for those who haven't been using LinkedIn for job searching, the below may be helpful.
If you find a position you are interested in but do not have a connection at that company, go into LinkedIn home and type in that companies name in the Search box, then click the Companies tab and click on "see all employees on LinkedIn". You can then filter on 2nd connections to see who is connected to your direct connection. Using this I reached out to my connections to explain that I was interested in a particular job at Company X, and that they are connected to Mr/Mrs Z at that company. Depending on your relationship with your connection, and their relationship with their connection at the company you are interested in, they may be willing to reach out to them on your behalf. Using this approach, I got my resume into the right hands quite a few times vs. applying to a black hole.
Good luck!