Pan-European keyboard layout
eurokb is an installable keyboard layout for Windows (should work at least from Windows 2000 to Vista64) authored with Microsoft's standard Keyboard Layout Creator.
It provides access to almost all accented characters from Latin-alphabet languages, along with a basic Greek alphabet, IPA phonetics, typographic niceties such as quick access to smart quotes, and various other symbols.
It is supplied in two variants, based on the UK and US standard keyboard layouts, respectively. (UK keyboards have one extra key and a slightly different arrangement, which fits eurokb slightly better.)
For installation instructions see the included readme.txt. For details and a simulation of the keyboard layout itself see the readme.html file in the appropriate directory, or the online documentation below.