I have recently purchased Bookmarking Demon 4.0 at the knockdown $97 (only while it is in Beta testing), and here is my review:

Bookmarking Demon is a tool that allows the user to easily automate backlinks from High PR websites. These high PR websites are social bookmarking websites such as Delicious, Digg, FURL etc.

Bookmarking Demon automates the creation of accounts (although you still have to enter a few captchas). You can create as many seperate accounts as you like.

Once created, you just type in the url you want to bookmark & Bookmarking Demon automatically pulls up the title, description & tags from the webpage (and any other pages on the site.

You then pick the page(s) you wan’t to bookmark and click start bookmarking.  After that, you want the googlebot to visit the bookmarking sites quickly so they can follow the links back to your site.

In order to speed this process up, you can then ask Bookmarking Demon to ping the relevant page on each social bookmarking site.   This is automated too - just hit the start pinging button.

If you bookmark your sites too often, these sites may treat you as a spammer or self promoter ban your IP Address.  Bookmarking Demon has features that help to minimize the spamming of bookmarking sites.

In the preferences, you can choose a certain percent of your bookmarking sites to submit your posts to.  I submit posts to 25 - 30% of the bookmarking sites each time.

It also gives you the option of adding a list of rss feeds so that every time you bookmark one of your own sites, it will also bookmark a news story from another site - this makes the bookmarking look more natural.

BMD 4.0 also has a built in Spamometer:

This shows you if your bookmarking efforts are likely to get you banned or not.

If you do get your IP Address banned, BMD 4.0 allows you to enter proxy IP addresses too.

Overall then, I think Bookmarking Demon is the best social bookmarking software available.  It enables you to get you new sites indexed quickly, Improve rankings & link love of your current sites and gets traffic to your website faster than conventional linkbuilding.

You can get bookmarking demon  for half price  on the following link  - Bookmarking Demon review.