A high percentage of Recruiters will immediately look at any social network sites on which you have posted information about yourself. Make sure that any information to which they may have access represents you in the best way possible. Party pictures are best avoided!
Ensure that the profile you may have posted on sites such as LinkedIn reflects the requirements of the company and role for which you have applied. Make sure that your public profile matches your CV in every way in terms of factual information.
It is always advisable to look at the profile of the person(s) you are meeting with at the interview. If you have any areas of common interest that can assist during the interview, mention them.