A web page hosted on a web server or blog server which supports tagging, might have the tags Baseball, Red Sox, Tickets, Away Games, and Discounts. A human reader can probably tell the purpose of the page by quickly scanning the list of tags. Typically, the server would display the tags in a list on that page, with each tag displayed as a web link leading to an index page listing all web pages which use that tag. This allows a reader to locate quickly all pages which have been associated with the term Red Sox. If the server supports tag searching, a reader would be able to find all pages that use a particular set of tags, such as Red Sox and Tickets.
It’s not much of a tag cloud yet, though, since only two entries are tagged right now, but hopefully I’ll get around to tag everything some day.