I live in Denmark and when the iPhone 3G came out there, you only (legally) had one choice of phone provider. A company called telia which has the worst 3g coverage of all the companies. It also costs 100$ (600 DKK) per month to have which is quite a lot. After the first 6 months you start to pay 67$ (400 DKK) but I am looking out for other providers.
I have looked at https://www.bibob.dk/ which has very phone calls and text messages but 1 MB costs 17 USD cents (1 DKK). So I am currently checking out to see how many MBs I use when I browse the internet one hour using PdaNet on my jailbroken iPhone. I am writing this blogpost while waiting that hour.
The company that provides the best 3G coverage in Denmark is soon going to make an offer for all the iPhone owners and I am very excited about what they will provide and at what cost.