Yasiv is a visual discovery engine.

reddit visualization shows how subreddits relate to each other. The data is based on subreddit description. A link between two subreddits means one has a reference to another. Thus if subreddit has a lot of subscribers but no links to related subreddits it will be flying lonely in space.

You can also paste links from Reddit into the search box to visualize particular subreddit or use bookmarklet - it should work for Reddit.com also. Multi reddits are not supported yet, but I will add them if necessary - just let me know.