There are a lot of ways which you can use to generate content for a blog and bookmarking, in your definition, is not recommended by me. Your blog will never be successful if it only 'leeches' content from other blogs unless your site is able to sort the content and shows what are the topics that are hot right now. (see techmeme.com)

Bloggers get their content because they know their stuffs. They are either in the trenches themselves (doctors blogging about diseases), recognized industry experts or they read a lot about their topic. It is what they are exposed to everyday that gives them the idea about what to write on their blog.

Another way to create content for a blog will be to request content from third parties. This can come in the form of guest posts where related experts are invited to write a post on your blog or interviews. People love interviews and all you need to prepare is a set of good questions.

I hope my reply helps.