Posted from the PHYSLRNR listserv.  This resource looks very nice, useful and well-organized.  You can browse by topic (looking for a teaching activity on atomic physics?) as well as a wealth of other resources (click on PER-Support to look for assessments or how to use active engagement in the classroom).

The AAPT, through COMPADRE has just launched the Physics Source; its digital library portal
for introductory physics courses.

The purpose of the “Source” is to catalog quality resources that are appropriate for introductory physics teaching and make them easily available to teachers of these courses. With your help, I hope that we
can make it our “source” for introductory physics teaching resources.
Please consider doing the following:

1) Remember to use the site when looking for intro phys information.
2) Improve the site by rating content and sending us critiques or
suggestions for improvement.
3) Suggest resources you use but could not find in the site.
4) Suggest resources that you have authored/developed and that are not
in the site.
5) Consider having COMPADRE host your content if it is currently
hosted at an unreliable server.