Foldr Monitr is a free tool that runs in the background and watches a selected folder (and optionally subfolders) waiting for you to add photos to it. When photos appear in the folder, Foldr Monitr automatically uploads them to your Flickr account for you.

Set it to watch the location you transfer your photos to from your camera and they'll be automatically sent to Flickr straight away. Photos can also be uploaded to a chosen set or to automatically generated sets based on the names of the subfolders in which they reside on your computer.