Here is one excellent Wordpress plugin which will give you possibility to have enormous amount of images for your Wordpress Blog.
WordPress › Flickr Shortcode Importer � WordPress Plugins
Basically after you install and setup plugin, everything on Flickr is on tip of your fingers.
Setup settings of plugin to suit your needs (source image size, destination image size, giving credits to author, seo friendly names, import of videos, setting up needed wrappers, etc...).
Process of adding images is going like this:
1. Locate image on Flickr licensed under Creative Common or GNU GPL license (do not forget to check option for giving credits in the plugin settings).
2. Embed image using Flickr html embed code (available on each image).
Repeat number 2. until you filled your post as much images as you wish.
3. Check Import Flickr images on post edit view (Plugin will copy images to your server, resize them as defined in media settings, rename the images and insert image sizes as specified in plugin settings).
4. Hit "Publish" or "Update" button.
Flickr images will be imported to your blog according to given settings of plugin and media settings of Wordpress. Easy as pie, no more slow searching for free images, resizing, uploading, inserting... You are now using powerfull Flickr search engine and this plugin to handle rest of the tasks.
You basically populate post such as this for under a minute:
Tourist Playground � Top Ten Longest Rivers In The World