I did a serach on the internet for other bookmarking sites and came accross Top 5 social bookmarking services. According to Pandia the top 5 are; Furl, Netvouz, Del.icio.us, Ma.gnolia and Bluedot.  My computer would not allow me to look at Furl and Bluedot it didnt find.  Ma.gnolia has shutdown.  Netvous and Del.iciou.us both came up when I searched them.  The article was printed on 28 November 2006.
The most recent list of Bookmarking sites that I can find it Five best bookmark management tools which was published on 16 May, 2010.According to this list, the top 5 are: Weave (an add on for Firefox - web browser), Xmarks, Diigo, Delicious and Google bookmarks.
I like the idea of using Google bookmarks, as I have a gmail account with them and for me it will all be in the one place.