There’s an app for that, but it’s email marketing that keeps me coming back.

Last summer, I switched from Verizon to AT&T because I wanted the iPhone 3GS. Since then, I find myself testing out whatever app is receiving the most buzz in an effort to understand why it’s popular and to see if it has any implications for our business or clients.

In the past six months, location-based apps have received a lot of attention. I’ve been testing out Foursquare, Gowalla and MyTown, three of the most popular in this category. If you’ve tried more than one, you know they are all unique. However, the common factor is they all rely on the “check in” and recently Google, Yelp and others have joined the party.

I like to “check in” but sometimes I forget to do it. With that in mind, it’s really the personalized emails from Gowalla that makes the difference for me. Each week, I receive a “Round Up” email from Josh Williams, the Founder and CEO of Gowalla. This recaps my activity, shows what my “friends” are up to, thanks me for me for using the app and asks for my feedback.

It’s quite possible that I missed an opt-in at some point during the sign-up process for Foursquare, but I only receive emails from them when I get a friend request or earn a new badge. These emails feel automated and transactional. The emails from Josh at Gowalla feel personal, relevant and timely.

This multi-touch approach, and the interplay between the app and email, makes me more likely to use Gowalla. The emails provide interesting content that’s easy to digest. They also do a great job of presenting my activity in a way that makes me reflect back upon the week. Josh freely admits these emails are a work in progress, and we could do another post on how they could be improved. However, the fact that they are using email this way is a great start and a clear differentiator.

How do you interact with apps beyond the in-app experience? Do you receive emails from any apps you use? How does that impact your usage?

Brady Sadler is the Director of Business Development for Griffin York & Krause, a marketing innovation company in Manchester, NH. Follow Brady on Twitter and find out more about his new passion, dishKarma.