Tell your friends about this one: We've got a free gift for those who sign up to receive our weekly E-mail Update newsletter (which, coincidentally, is also free).

What is it? Our Best of the Photo Detective 42-page digital download, containing photo historian Maureen A. Taylor’s best tips for identifying mystery family photographs.

After you submit your newsletter sign-up, you’ll get a link to download the booklet. It’s a PDF, so you’ll need the free Adobe Reader software to open it.

And yes, if you’re already a newsletter subscriber, you still can get the download. Go to the sign-up page, enter the same e-mail address where you already receive the newsletter, update any other preferences you want, and click Submit. We won’t send two newsletters to the same e-mail address.