Wordle is a really fun service which can create tag-clouds from text och tags from your account at del.icio.us. You can see one I created on the image above. I also saved it to the gallery on Wordle if you would like to see my tag-cloud in bigger format.
Social bookmarking is everywhere these days. If your're at home building the next amazing del.icio.us- or digg-clone it's important you plan the design of the database carefully. Philipp Keller shows a few variations on the post "Tags: Database schemas" and gets an enormous response in the comments.
Also read "Explaining and Showing Broad and Narrow Folksonomies" by Thomas Vander Wal (the man who coined "folksonomy"). Interesting reading about "broad" and "narrow" ways of user-tagging.
Quintura is a really interesting new search service where the results is presented in a visual manner. If you search the name of our company is looks something like the picture. Normal links are presented in the lower part.
On my web site there's not that much content yet. But I feel I need to upgrade my categories soon and perhaps add a tag cloud.
Jason Kottke is having similar thoughts and writes an interesting post about how to calculate how much the popularity of the tags are accelerating. In this way you can produce a list of tags that represents what's been going on recently on the site. Sort of like the "hot tags" on Flickr.