Hiking, Skiing and other related Map apps
Maprika: (iPhone and Android) This is a free program for displaying an existing map they have on file or taking any map and making it a GPS enabled map. You can then display the map with your location shone on it. Unlike the regular map application, you do not need to have web access. You do need a cell phone connection to use the option to see where friends are. Also the map is one geared to what you want to see. For example you start with a map the emphasizes tourist attractions or trails. Most ski areas and big places like Disney Land are already covered. Your neighborhood park probably isn't.
This is best explained with an example. Assume you want a map of Paris France and you are somewhere where you have internet access. You first start out by seeing if anyone already uploaded one. When I checked, someone had but it did not cover enough of the city. In this case you need to make a map of your own. To do this you need a picture of the map you want. Either take a picture of a map from a guide book or a sign, scan in a map from a guide book, or find a map online. It will have to be in the .JPG format which is the format that pictures stored on iPhones and probably other smart phones use. You then have to add the GPS data to the map. This can be done on your smart phone but it is MUCH easier if you do it on a PC. Their web site has a lot of useful information.
Their web site is http://www.maprika.com/ The app is available for the Android and iPhones as well as tablets. You can see friends on either system assuming you have a cell phone connection.
I put together a bunch of user notes that supplements the info online or just states it in a manner easier for me to understand. Click HERE to see it. It also includes notes on how to convert .PDF files to .JPG files because sometimes the only format you can download the map in is .PDF.
Note. Maplets is a similar app. Costs $2.99 and has more maps. It is harder to add GPS data to the maps and most maps do not have GPS data. If the map does not have north basically up and is not to scale (which is often the case for ski area maps) then is almost hopeless to put in GPS data. The app assumes the map is to scale when adding GPS data. The maps themselves are free.
GTM, Green Trails Maps (iPhone and Android) This free app allows you do download the more popular Green Trails enhanced topographic maps. The maps cover portions of Arizona, British Colombia, California, Nevada, New York, Oregon and Washington. Some states are quite limited, the only British Columbia one is Whistler. On the other hand there are 93 in Washington. Most are $0.99 but they go up to $4.99 for Mt. Rainier (although Mt. Rainier East or West are only $0.99 each.)
The maps look just like the printed Green Trails maps and have plenty of resolution. They have significant enhancements over the USGS maps. For example, the Snoqualmie Pass map shows the cross country trails maintained by Summit at Snoqualmie and the State. They display your location and direction on the map and do not require a internet connection except to initially install the map.
If you need to reinstall a map, you may have lost, for example you upgrade to a new phone, you will find that the map is not backed up on your desktop. The fix is to repurchase it. It looks like you will have to pay again but it will recognize that you have already purchased it (after you re-enter your iTunes password) so the download will be free the second time. It works this way with the iPhone and I assume the same way with others. It does behoove you to keep a list of the maps you have purchased, I have purchased: Sno Pass Gateway(207S), Snoqualmie Pass (207) it goes further east, Tiger Mountain (204S), Rattlesnake Mtn (205s), Thorp(242), Lake Kachess (208) and Easton (240), Mount Stuart (209), Monte Cristo (143), Mount Rainier (269S), Stevens Pass (176, Just the area form the pass south), Benchmark Mtn (144, The area just north of Stevens Pass).
They are not good about answering e-mails and have hid their phone numbers.
Topo Maps: http://topomapsapp.com/ (Has LOTS of useful information.) iPhone and iPad only. The iPad version is specifically formatted for the iPad.
The app is $7.99 and the maps are free. The maps are just what the USGS and the ones the corresponding Canadian organization puts out so some are way out of date. I have not explored this app in detail. If you are interested in an area coved by the green trails map, you are better off paying for the map although this app has a number of extra features that the Green Trails ones do not such as measuring distance and bearing, showing what is visible, type in coordinates, and view from other apps. You can add, manage, export and view waypoints and display waypoints on the map.