Tiny URL
This site allows you to shrink down those long URLs. For instance, let's say you want to send a friendly this neat link to pictures of old library catalog cards. But look at how long this link is!
http://images.google.com/imgres?imgurl=http://www.library.upenn.edu/
exhibits/pennhistory/library/cards/card4.gif&imgrefurl=http://www.library.upenn.edu/
exhibits/pennhistory/library/cards/cards.samples.html&h=215&w=362&sz=50&tbnid=
a7MoPpd1_VIJ:&tbnh=69&tbnw=117&hl=en&start=2&prev=/images%3Fq%3Dlibrary%2Bcard%2Bcatalog%2Bcards%26svnum%3D10%26hl%3Den%26lr%3D%26rls%3DRNWE,RNWE:2004-09,RNWE:en%26sa%3DN
Not very manageable, is it? However, if you go to http://tinyurl.com/ and plug in the link above you get this much more usable link: http://tinyurl.com/2xsk6x
Del.icio.us
This site is a social bookmarking site. Once you set up an account you can bookmark any site in order to share it with others. Professors might want to set up an account for a particular class with a list of sites that will aid students in the course!
Here's a test site I set up: http://del.icio.us/uwslibrary