At work, we are going to be bringing on a lot of European customers over the next couple of months, so my current project is the Globalization of our web application. Not a small undertaking as any who have done so will already know.
When we originally wrote our web app, we did not take any Globalization into account. Our web app was first written using the .NET beta version and I do not think any support existed for globalization, but now that we are on .NET 2.0, there is quite a bit of support.
One of the first things I discovered was the .NET CultureInfo object in the System.Globalization namespace. Most of our web pages derive from a custom Page object, and in setting the Page.Culture object in the custom page with the user's preferred culture, .NET did most of the work in reformating dates and numbers. I did however have to go through and remove a bit of custom date formatting that was being done throughout the app.
I have also discovered the TimeZoneInfo object, although I have not actually started using it yet. This object allows easy time conversion between time zones as well as to/from UTC and local time zones. However, before I can start using this, I need finish converting all of our Database datetime columns to be UTC instead of our local EST.