The social bookmark explosion continues. Not just for storing and organizing your favorite sites: bloggers, marketers and SEOs have take to social bookmarking as a way to build backlinks, PageRank and SERP standing.

Ajaxflakes just published a new list of over 300 social bookmarking sites, “all tested and live”. Although the categorization is a tad murky [should I look in "niche". "special", or "misc."], there’s a lot of good content to sift through. Each listing includes the site’s PR and a brief overview. A few of the niche bookmark sites I use are missing here, but there’s a whole lot more to explore.

Finding the sites is one thing, using them effectively is another. The key here is to develop a strategy based on your market, and distribute your information efficiently. There’s no better tool available right now than Social Marker, a one-stop site that speeds you through up to 32 of the more popular bookmark sites with unmatched ease.

Now if only I could combine these two into one customizable mashup….