TinyURL.com - where tiny is better!
A handy service, though of course if it goes away the URLs will all break. Best used for transient content. Typical use is you want to send a URL to a friend, but email handles it poorly. A very valuable use would be to to tell someone a URL by phone, or transcribe one to a PDA, or write it on paper. Since TinyURLs are of the form:
one could simply write "jiok" and know to reconstruct the url by prefixing http://tinyurl.com/.
For bookmarking etc. one should store the permanent URL.
PS. Note the web site now uses Google ads. This is an insidiously wonderful scheme that may keep this service viable.