Foursquare Klout If location-based check-in service Foursquare is your social media poison of choice, then your Klout score is likely to rise substantially.

Klout, a site that measures a person’s influence based on social media activity from Twitter, Facebook and LinkedIn, announced today that its adding Foursquare to the list of social services that will determine a person’s Klout Score.

Klout has determined that active Foursquare users who provide useful Tips are the most influential because they have a major impact on how people make purchases. Tips, for those not familiar with Foursquare, are short messages that are associated with a specific business location and pop up when followers check-in.

“The importance of tips for a venue cannot be underestimated. Tips are loved by users and change what customers want,” the company states in a blog post. Two-thirds of active Foursquare users leave tips and 80 percent of them have used a tip from someone else, according to Klout’s observations.

Klout has also added the ability to link YouTube accounts to a Klout profile, although activity on YouTube won’t affect the overall Klout score at this time, according to the company. It will be interesting to find out which behaviors Klout identifies as influential for YouTube usage.

The addition of Foursquare by itself strengthens the credibility of a person’s Klout score by providing a more accurate assessment of influence. So, it’s to Klout’s advantage to integrate additional social networks (like Instagram and eventually Google+) into its influence measurement in the future — especially since not being active on networks you don’t use doesn’t count against your score.

What social network do you wish was included in Klout’s influence measurement?