  if you've ever wished that you could access your bookmarks from any computer, then you should check out urlLink del.icio.us , which is a web site that allows you to do exactly that (you can check out urlLink my list of bookmarks here ). in addition to simply bookmarking sites, you can categorize them with multiple tags, so links don't have to live in the strict hierarchy that browsers force you to use.
urlLink mike sippey points to a tool that allows you to visualize the prominence of the semantic tags on your bookmarks ( urlLink here's the visualization of my del.icio.us page ). btw, the visualization is not a server-rendered image: it's all done with plain text and css positioning. pretty slick. unfortunately, i don't think that the distance between terms has any relation to their relationships though. 
