I downloaded Mammoth tracks recently from the play store. Its from the same people that make the guthook apps for the AT. I'm still playing with it, but looks like a nice addition to the IAT atlas and guidebook. Comes with Kettle Moraine section, the other sections can be downloaded via in-app purchases.

When I downloaded it, it had some issues, specifically it wouldn't work on my S7, but Alice, the developer contacted me within a couple of hours and had the app fixed in about 24 hours. Unexpected and very nice to get that kind of response.