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/