Program: AllChars for Windows
License: Open Source, freeware sourcecode available.
Description: Best Free Software 2007 PCmag, lets you type foreign characters like ü in any application. Tap hotkey (Ctrl) followed by two characters such as u and double quotations, combined character appears in your document. [you can also use to type curley quotes]
additional: Loaded on my USB drive, runs fine using Pstart to launch. I don't know how to tell if it is writing anything to the registry.