There are three for me: Digg.com Stumbleupon.com and Delicious.com. These are the biggest and I find these the easiest to use.
Hi, Check in google High PR. Social bookmarking sites. Some HIgh Free PR Sites. reddit Delicious Technorati.com StumbleUpon.com Squidoo Mister-Wong Wikio Digg Furl.net Hostmonster Slashdot Digg BibSonomy blinklist.com Newsvine
In my opinion automated tool is not very useful.Your detail will be not properly fill through automated tool.So avoid it and do only ethical way.
yes, manual bookmarking still the best but if you want to make your work done easily and fast you can use some social bookmarking tools.
I bought socialbot and I have to say that I don't like it. I gave up using it... Maybe they will have a new update for this software soon.