Social bookmarking is a very useful tool to keep track of websites. I have a delicious account for both my patrons and personal use. It is very easy to direct students to the list of recommended sites. However, sometimes they don't understand the concept that I am only recommending sites linked from the school account. They immediately go for the search engine even though I tell them that they will have to go through the website evaluation process if they use a site other than the pre-approved ones.
Since Sears doesn't always use the most obvious choice it can be frustrating at times, one does realize its value when tagging. There are many ways to say the same thing, and as a social bookmarking account grows, if tags aren't consistent it can be easy to lose track of links.