Some social bookmarking sites will label you as ‘Self Promoter’ if your bookmarks contain nothing but your own domains. The solution to this is to hide your url among other links that are not related to yours.

For every url you want to bookmark, you should bookmark another 3 to 4 bookmarks that are totally unrelated to your site. Make sure those sites are not your competitors.

No idea what urls to use? Just go to any of the following and grab any of the urls there and mix them with your urls.
Always stay under the radar and make your social bookmarking accounts look more legit.

http://technorati.com/blogs/directory/ entertainment
http://technorati.com/blogs/directory/sports
http://technorati.com/blogs/directory/business
http://technorati.com/blogs/directory/lifestyle
http://technorati.com/blogs/directory/politics
http://technorati.com/blogs/directory/ technology
http://digg.com/world_business
http://digg.com/science
http://digg.com/gaming
http://digg.com/lifestyle
http://digg.com/entertainment
http://digg.com/sports
http://digg.com/offbeat

You can also bookmark pages from video sites from youtube, dailymotion, etc.
Most people will bookmark funny videos, pictures or some forum discussions.
Mix it in and you will be able to pass a visual inspection.