The British Library has uploaded a million+ vintage photographs and scanned images to Flickr. These are now in the public domain and can be reused. It is a great place to get images for family history projects and presentations. The images are arranged by albums which include advertisements, fashion and costumes, heraldry, maps, portraits, ships and war.
TIP: This photostream can be searched using the magnifying glass icon located under the menu bar on the right side.