What do I need to know to globalize an asp.net application?
A couple of things that I've learned:
Absolutely and brutally minimize the number of images you have that contain text. Doing so will make your life a billion percent easier since you won't have to get a new set of images for every friggin' language.
Be very wary of css positioning that relies on things always remaining the same size. If those things contain text, they will not remain the same size, and you will then need to go back and fix your designs.
If you use character types in your sql tables, make sure that any of those that might receive international input are unicode (nchar, nvarchar, ntext). For that matter, I would just standardize on using the unicode versions.
If you're building SQL queries dynamically, make sure that you include the N prefix before any quoted text if there's any chance that text might be unicode. If you end up putting garbage in a SQL table, check to see if that's there.
Make sure that all your web pages definitively state that they are in a unicode format. See Joel's article, mentioned above.
You're going to be using resource files a lot for this project. That's good - ASP.NET 2.0 has great support for such. You'll want to look into the App_LocalResources and App_GlobalResources folder as well as GetLocalResourceObject, GetGlobalResourceObject, and the concept of meta:resourceKey. Chapter 30 of Professional ASP.NET 2.0 has some great content regarding that. The 3.5 version of the book may well have good content there as well, but I don't own it.
Think about fonts. Many of the standard fonts you might want to use aren't unicode capable. I've always had luck with Arial Unicode MS, MS Gothic, MS Mincho. I'm not sure about how cross-platform these are, though. Also, note that not all fonts support all of the Unicode character definition. Again, test, test, test.
Start thinking now about how you're going to get translations into this system. Go talk to whoever is your translation vendor about how they want data passed back and forth for translation. Think about the fact that, through your local resource files, you will likely be repeating some commonly used strings through the system. Do you normalize those into global resource files, or do you have some sort of database layer where only one copy of each text used is generated. In our recent project, we used resource files which were generated from a database table that contained all the translations and the original, english version of the resource files.
Test. Generally speaking I will test in German, Polish, and an Asian language (Japanese, Chinese, Korean). German and Polish are wordy and nearly guaranteed to stretch text areas, Asian languages use an entirely different set of characters which tests your unicode support.
Learn about the System.Globalization namespace:
Also, a good book is NET Internationalization: The Developer's Guide to Building Global Windows and Web Applications
Would be good to refresh a bit on Unicodes if you are targeting other cultures,languages.