I thought it would be useful to start a collection of Portable Class Libraries for developers to help them target multiple platforms with as much shared code as possible. Below is a list of links that will bring you to the PCL’s Nuget/Codeplex/Github location. If you have a PCL you’d like to add to the library, let me know and I’ll add it immediately.
Check out this complete list of all the APIs available to PCLs
Windows – Windows Phone – Xbox – MonoTouch – MonoDroid
Zxing Barcode Scanning Library for MonoTouch, Mono for Android, and Windows Phone from Jonathan Dick (@redth)
As you can tell, this is a work in progress! It will be up to us as a community to populate this page with awesomeness.