Real estate is important
With all the great info we want on our pages real estate itself becomes quite valuable. Be sure to consider the space you are using for social buttons. Is there something more important that needs to go there?
The most valuable buttons
In our experience the most popular social sites are the most valuable. Sites like Facebook and Twitter. At least start with these and then maybe add more as they become popular. It's pretty simple to try out some different sites to determine which ones get you the best results over time.
Facebook Like vs Share
The share button was the first button that Facebook came out with just a couple years ago. Last year they introduced the Like and/or Recommend button. So which one is better? When the Like button came out you couldn't add your own comments, but that has sinced changed and really there isn't much of a difference. The Like button is easier to understand and use than the share button and based on the recent improvements with the Like button I'd stick with that one.
So, what are you trying to accomplish anyway? Are you just following the buzz words? Are you thinking there are tons of people using these social sites and how can you be a part of it? Whatever your reason and goal just be honest with yourself and make sure it fits with what is sensible.
Did You Know: Your dealer site inventory and library pages have the Facebook Like and Twitter Tweet buttons on them for your visitors to share with their friends!
Big list of social websites: http://en.wikipedia.org/wiki/List_of_social_networking_websites