Gebührenfalle is a nice looking application you can use to check your T-Mobile Germany account. All you need to have is an account for Mein T-Mobile and an iPhone or iPod touch.
You will get a monthly overview of all your contracts with the current minutes, prices you have to pay in addition to the monthly fees and the current sent SMS or transfered data (depending on your contract). You can also look at your billings history. Gebührenfalle works with a lot of German T-Mobile contracts and we support business accounts, too.
Gebührenfalle is available on the App Store for 0,79 EUR. You can find more details on our web site.
If you’re interested in beta testing, please give us a shot.