BMD4 has been out for a while now and has already been upgraded a few times. It now includes even more sites. After using this version for the last 6 months or so I can say that my favorite feature is the ability to add new sites that I find on my own. When I bookmark with BMD I am bookmarking to over 400 sites. This is truly kick ass!
There are a ton of pligg and scuttle sites out there. I use searchbot to find all the registration pages and simply paste the list into BMD.
Bookmarking Demon 4 is on the verge of officially launching. It is available here. It's only %60 of the full version. (Update: The full version has been out for a while) I have been testing it in beta though and I really love it. I already liked bookmarking demon 3 and I got tons of one way links with it, but bookmarking demon 4 is much better. It's actually not even an upgrade at all but an entirely new software! It really is. It doesn't look the same or anything. It's a huge, huge improvement.
It's got two modes, one for beginners and one for experts. Options are amazing too. The bottom line is that with bookmarking demon 3 you could create accounts at 20 sites but not all of them worked. Some you had to go to and set up the account manually but it was still pretty quick using bookmarking demon. But anyways, say out of 20 social bookmarking sites you would actually only successfully create accounts at about 10-14 sites.
Now with bookmarking demon 4 you can create accounts at 100 sites!! The beta version has just 58 sites but that's good for me for now. I'll take it. So everytime I bookmark a link it goes to 58 sites. That's 58 links. Actually it's more because for every keyword you enter it creates a tag at the social bookmarking sites. A tag gets its own page and thus you get another one way link.
(Update: My version of BMD has over 400 places to bookmark)
This is my favorite one way link building software for sure. I set it up to run huge amounts of links before bed every night. I also use it to get new sites indexed in less than 24 hours usually. Not to mention the traffic it brings. You can get some pretty good traffic from the social sites which is always a plus! I mainly use bookmarking demon 4 to get my anchored links. That's what matters most to me.