Gnickr
Gnickr allows you to manage photos on your Flickr site as if they were local files on your Gnome desktop. It does this by creating a Flickr virtual filesystem.

GratePic
Cross platform tool for posting, commenting and rating photos on flickr.

Desktop Flickr Organizer for Gnome
This application allows online/offline mode management of your photos. You can upload, search and download photos, through the easy to use interface.

Flickrfs Virtual Flickr Filesystem
Create a virtual userspace filesystem which allows easy uploading/downloading/searching of images through flickr.

KFlickr
A standalone Flickr.com uploader for KDE

flickrsavr.py
A python script that automates the process of saving the URLs (of public photos), and also saves a local copy of thumbnails, and stores descriptions, dates, and tags in a database.

jUploadr
A cross-platform uploader for both linux and windows.

FlickrClient
Python interface for the Flickr API.

FlickrUploadr
A tool for uploading pictures to your Flickr account.

Flump
Simple application that allows your to download all of the public photos for a specific Flickr account.