Social Bookmarking is a great way to store, tag and access websites and delicious and Diigo are two of the most popular social bookmarking repositories. Whilst many users decide to make their archive public which allows others to "piggyback" off your searching and filing, you do also have the capability to restrict access to your archive. Users are encouraged to organize their bookmarks with informal tags instead of folders or imposed taxonomies, although some services feature categories/folders or a combination of folders and tags. Delicious allows you to view bookmarks associated with a chosen tag, and includes information about the number of users who have bookmarked them. It also has RSS feeds that allow you to subscribe to others' archives. Remember that you can also search everyone's public delicious archives in much the same way that you search websites using Google.

As with many other Web 2.0 activities and tools, the good folk at CommonCraft have a great little video that explains Social Bookmarking in Plain English.

Here is another movie from Jeff Utecht that shows how to search delicious.

You might also like to check out the Using del.icio.us To Organize Your Favorite Internet Sites.pdf notes on searching delicious.

You can also use Getting Started With Diigo notes to help you set up and work with a Diigo account.