There's and app for that! .. and it's Photo Finder!
Photo Finder helps you find photos of anything you are searching for fast. You can zoom and rotate the photo and even save it to your phone or iPod touch.
Simply type any word or words of what you are looking for and the app will display up to 200 photos to choose from in a scrollable list of thumbnails. If you see a photo that you like simply click on it to enlarge. Once it's enlarged you can pinch, zoom and rotate the photo. If you want to save the photo you can simply press the save button and the photo is saved to your camera roll. Once you download the photo you can set it as your background, save it to your computer or email it to someone from within the iPhone photo gallery.
Check out the screen shots, the photos speak for themselves.
iPod Touch users will need a wifi connection to the internet.
This app uses the Flickr api and search's for public photos from Flickr. If you get a message that a certain photo is unavailable when you click on it that means that the owner of that photo did not make it downloadable.