Here are some ways  check-in apps can help your marketing:
1) They can drive  branding. We all need ways to sand out within our market space. If you have  interesting services and products, people will naturally want to follow you and  learn more. You will have succeeded in gaining their attention and notice.  Sometimes getting noticed in the online environment can be the hardest part.  Once a business has the attention of potential customers a rapport can be  developed and used for business transactions that can benefit everyone involved.  
2) They can drive  relationship building. The apps let you in on the daily routine of a person’s  life and this can help you get to know them better and seek common ground. For  instance if you see that friends are flocking to a restaurant or store you are  more likely to check-in as well. Foursquare is really good and cost effective  way to drive buzz for new services and products.  
3) People are  attracted to movement and action. If they see you moving about the world, taking  part in different events, different activities, you are automatically seen as a  “mover and shaker” – this can position you for opportunities and contacts.   
4) You can build  greater influence. You  can use your check-in status to make recommendations and  suggestions for those on your friends list. These can help you be seen as  conscientious and helpful. 
5) Finally, they are  fun. I love to see what other people are doing and to make note of the places  I’d like to try too. Again, the first part of all marketing is to get attention-  and the check-in apps can help you do this well. 
So if you have been  reluctant to start checking-in you might  want to reconsider. And yes, I’d love  to be Foursquare friends.