Here are two ideas I could have submitted to the SIMagine contest, but didn't. ;)
- Info Cards securely stored in your SIM: Florian van Keulen, one of Maarten's students did a project on different architectures for implementing Info Card on mobile devices. One of the options that Florian investigated was to store the Info Cards on the SIM. A handset resident application would then facilitate communication between the Card Selector on a different platform (a PC in an Internet cafe) and the SIM through Bluetooth.
- Turning an existing contactless smart card into a pre-paid mobile SIM application: You're not supposed to be able to clone an ePassport or contactless creditcard, of course. But you can do something else. You can pre-record some challenge-response pairs using an NFC handset and store these in an application on the secure element (SE, usually the SIM card) of the handset. If the application can authenticate itself to an inspection system (a POS terminal) then the handset can be used instead of the original contactless card. This improves convenience: one device instead of multiple cards, you now have a GUI. As for security: You can limit the number of challenge-response pairs, you can time-stamp the challenge-response pairs (the SE can connect to some trusted time server during enrollment), etc.