Social Bookmarks adds icons to your posts and/or pages that allow your visitors to easily submit them on social bookmarking and network sites.
If you don't use your own bookmark icons, nothing. Otherwise, the default folder location has changed - this is so that upgrading a theme doesn't cause them to go missing. Simply move your icon folder to your installations
wp-content folder for it to continue to work.
If you've not specified
default=on then new sites will not appear - you will need to specifically switch it on.
Here's an example of switching on LinkaGoGo...
<?php echo social_bookmarks( 'linkagogo=on', 'padding-left: 5px; padding-right: 5px' ); ?>
The icons provided with the plugin are the standard icons for each of the sites (usually the site's favicon). There are many good, free collections available. However, none have the full set that this plugin uses, which is why I use this generic group.
None-the-less, most people will probably only want to display a few, popular, sites and therefore various icon collections will be ideal.
Alternatively, read 75 Beautiful Free Social Bookmarking Icon Sets from Blog Godown or 21 Sets of Free Social Bookmarking Icons for Your Blog from wpzoom.
I keep a huge database of over 500 bookmarking services. However, I only use those that appear to be the most popular, based on Google search results. If you think I have missed one of great importance, please request it on the forum and plead your case!