My first real mobile app is available for download now from GitHub and hopefully soon from the Nokia Store.
It's an implementation of the Google Authenticator for the N9.
This is the one killer app I needed to convert to my N9 fulltime from Android.
It generates the same codes as the Android version and can be used, for a single account at the moment in the same way.
I hope this is of use to some N9 users out there.
For more information read the details at GitHub (it's open source) and download it from there too. Note that you must have Unknown sources turned on in your application settings until Nokia approves.
I have my own ideas but I am soliciting for what I should try to port next. Please leave comments!