Advanced User Guide for Flickr

useful:
Flickr Advanced User Guide
includes useful tips such as how to specify the photo privacy level when uploading imgs per email:

e.g.

• foo13bar+friends@photos.flickr.com – Visible to friends
• foo13bar+family@photos.flickr.com – Visible to family
• foo13bar+ff@photos.flickr.com – Visible to friends and family
• foo13bar+private@photos.flickr.com – Only visible to you

further tips:

http://lifehacker.com/software/flickr/