Here’s a great site that should make it extremely easy to find photos related to a particular topic. Type in a tag like “beach” and it’ll show you a sun surrounded by planets named with related tags like “ocean”, “sea”, “sand”, etc. By clicking the planets you can drill down to more related tags or click on the sun to get photos with those tags from Flickr!
It shows the photos in a nice sphere where you can click to see a bigger version.
Its worth visiting – Tag Galaxy