I get this question a lot. And it is a good question. There are so many different social bookmarking sites that it is hard to make your choice. The easy answer to this question is the same answer as for any choice of social media. Be where your customers are.
Ok, I understand. A little more detail would be helpful. So, let’s look at it in more detail. You want more visitors, but only if they are genuinely interested in your business, right? I would always pick at least one of the large social bookmarking sites, such as digg and/or delicious. There are so many people using these platforms, that there is a fair chance that there are people that are interested in your business.
Secondly, I would use one of the many tools that are available today (e.g. OnlyWire) to instantly bookmark what is of interest to you to a number of social bookmarking sites. You can pick any number of sites that is available. Just make sure to also bookmark other sites of interest to you.
Thirdly, I would look for social bookmarking sites that are specializing in your field. E.g. you are a financial guru. 
You definitely want to join “Tip’d'”, a social bookmarking site that is meant for those with finance as there niche. To give you an idea, Tip’d has the following categories you can post to: business, commodities, currencies, economy, funds and ETFs, green, personal finance, real estate, stocks, tech, entrepeneurship, videos. As you can see, this is a not a site for everyone.
Another great example of a social bookmarking site that is highly specialized is carnivalofpolitics.com. As you probably already guessed, this is all about politics. Your topics should fit one of the following categories: left, independent, right, humor, local, state, national, world, other, or elections if you want to post on this site.
You can imagine how powerful it can be to be a part of a social bookmarking site that covers your topic! And there is one for any topic imaginable.
