Flickr

There is a way to add tags to your Flickr posts. Start a new line in the body text (not the caption) and write "tags:" followed by your tag words. Separate tags with one space between each word, or use quotation marks for multi-word tags. See http://www.flickr.com/help/photos/#140 for examples.

Remember, when using Share Online with Flickr, the username and password is different from your normal Yahoo! login.