Del.icio.us allows its users to create bookmarks, however since it is web based, they follow you everywhere. That in itself isn’t what makes del.icio.us powerful though, it’s the community driven aspect of it. People bookmark a site because it is useful to them in some way, so in short del.icio.us is providing a huge shortlist of excellent bookmarks cultivated by other internet users.
The acquisition of del.icio.us is the second such purchase for Yahoo! this year, after acquiring Flickr toward the end of March 2005. Flickr is a social image sharing website, where they allow their users to categorise and tag photos. Clearly Yahoo! can see an incredible market in the community or has a use for the tagging type nature of these sites as they supposedly paid between US$30-40 million for each of them.
Congratulations to the founders of both of these sites, it just goes to show what a good idea and some leg work can get for you.