We previously covered Downloader, a free Windows only tool that lets you download Flickr photos in their largest available size to your local computer.
You can search and download pictures from Flickr or you may download photos that have been uploaded or favorited by a particular user. The EXIF data is preserved for the downloaded pictures.
Downloadr is available only for Windows but if you are on Mac or Linux, you may consider using Bulkr. This is an Adobe AIR utility, free of course, that also lets you backup or download all your Flickr photos in just one click.
Bulk also supports resumable downloads. You may download Bulkr from clipyourphotos.com/bulkr.