Those people wandering around Northeast last Saturday afternoon wearing T-shirts that read "Field Trip" weren't refugees from a tourist bus. They were beta testers for a new Android app that Google tried out in five markets, including the Twin Cities. With Dusty's Bar serving as base camp, the 250 or so participants who downloaded the app walked, biked or drove to a couple dozen points of interest around the 'hood, like artists' studios and the seldom-opened old Hollywood Theater. A surrogate-Siri tour guide alerted them as they neared the next attraction, then gave a back story on it. On IW's device, the gravelly-voiced guide sounded more like Bart Simpson's aunts than serene Siri, but it's a fun tool for autonomous exploration and discovery of less- obvious neighborhood gems -- and a great way for the advertisers Google hopes to attract to reach people who are walking right past their doors. Future events may be in the works, said Kate Iverson of Permanent Art & Design Group, which developed the local content, but the app for Northeast can be used any time and will continually be expanded. An iPhone-friendly version is in development. To download, go to www.fieldtripper.com.