Jon Udell's January 25, 2007 blog post Unintended consequences of syndication is an interesting read, especially if you're trying to figure out your personal bookmarking strategy.
I've been thinking about my own bookmarking "strategy" ever since I learned that my favorite tool RawSugar's days are numbered. I also use ConnectBeam (to track the comments I leave on other blogs), Cogenz (for posts related to project management), and occasionally BlinkList (for tagging posts related to innovation management). Now I've started to use del.icio.us. as a general purpose tool. (To see a more complete list of the available tools, see Ismael Ghalimi's post here.)
The reason for my personal variety is partly to learn about tools, and partly because I use these tools to support personal and client research.
I haven't really gotten into the "social" parts of bookmarking. By that I mean that I use the tools as personal research support, not for sharing. The benefits I get from seeing what others are bookmarking have not been that substantial so far; I haven't really tried. I've also used "keep private" features while bookmarking on some client projects in order to prevent others from seeing what I've been researching
Udell's article points out some issues with the widget he uses to create a and display a stream of bookmarks on his web page. He would like the ability to be somewhat selective with this since (a) some bookmarks he defines are private and (b) only links associated with certain tags are appropriate for display.
So far, letting others see what I'm bookmarking in a display on my blog is not a great desire of mine; if people want to see my public bookmarks on del.icio.us, they can go to http://del.icio.us/ddmcd and check out the paltry few I've parked there so far. That number will be growing as I switch from RawSugar.