crwlr
Library for Rapid (Web) Crawler and Scraper Development
... just load actually all links it is finding (and is allowed to load according to the robots.txt file), then it would just load the whole internet (if the URL(s) it starts with are no dead end). Or it can be restricted to load only links matching certain criteria (on same domain/host, URL path starts with "/foo",...) or only to a certain depth. A depth of 3 means 3 levels deep. Links found on the initial URLs provided to the crawler are level 1 and so on.