There used to be but I believe a member privacy or third party issue came up or something. Either way, I believe it was taken down to protect HAMBer's. I believe there were also a bunch of maintenance issues as well and the app host was charging way too much or something. The app also didn't seem to play nice with the web-based forum and vice versa. It seemed to be a combo of problems.
Just use your web browser. I put a ****on on my phone home page that opens the HAMB site on my favorite starting page. On Android, just surf to the page you like to start with on the HAMB. Click the three dots on top right corner of browser. Click on 'add to home screen'. Then click 'add'. You may have to drag the newly created HAMB icon to the top-most home page.