Delicious has been around for quite some time - previously it was http://del.icio.us, bought over by Yahoo. Yahoo kept with it for about 2 years and then sold recently to the founders of youtube. After the latest acquisition, delicious has undergone a major change in appearance and features, I shall come to those separately.
Right now, to the basics of Delicious.
There are so many links that are coming in our way (emails, tweets, blogs, facebook, photos, videos etc etc) and we keep reading those jumping from one to another. After a few days we encounter a situation where we want to refer back to a particular web page that we previously visited. Sometimes we forget where we got access to that page and invariably do a google search or a specific search in our emails (multiple), twitter, browser history etc.,
Delicious helps in aggregating the links, so that we can go back and refer to whenever there is a need. One or more "Tags" can be applied to each link that we save which further helps in consolidation. One can mark a particular link private or public (by default). The search feature helps in searching for content as well as tags.
The browser extensions / add-ons help in saving the links quickly. For Chrome there is an extension which helps saving much easier! With the help of applications like twitterfeed, one can auto-tweet when storing in delicious! More options of integrating twitter and delicious can be found here.
Another useful tool that delicious provides is "feeds". It provides a generic syntax for various kinds of feeds which are available in this help page. Using which, one can set his reader to keep abreast of the links of a particular user, in a particular tag, or a combination of both and much more.
An off-the-track application would be using this for people working in small teams. Several team members can share a link with a mutually agreed tag and subscribe to the feed of that particular tag. If anyone finds a link which the team needs to read, he can save it applying that particular tag. Automatically a new item will appear in their corresponding subscription!
