What is Isis? Well, if you have a smart phone with the ISIS app (Including: Samsung Galaxy S, LG G2 and DROID RAZR, MAXX & ULTRA but it is currently not available for iPhones) and the ISIS enabled SIM card you are ready to go! ISIS is an app that stores your credit card and store loyalty cards for you right on the phone. No longer will your keychain be filled with different store loyalty cards and you don't have to carrry your credit cards with you (which I don't do because they are in case of an emergency!).
If you don't want to associate a credit card with ISIS you can open an American Express Serve account which enables you to place money in the account that you can utilize for shopping. I have been a long time user of Serve so when the app becomes available for my phone I'll be using serve. I really like it because I can stay within budget without fear of overspending if I see an item!
To use ISIS, you simply swipe the phone at any merchant that uses contactless payment options. Check here for a full list. And if you are worried about security, you can feel secure because to acces ISIS you must set a personal code and all of your credentials are stored on a chip in your phone that is separate from the phone's main operating system and hardware. Additionally, all of your transactions are between you and the merchant, so your privacy is intact.
Here is a video that provides an explaination of ISIS. As I mentioned I don't yet have access to ISIS but I look forward to the day I do!