Atlas Quest - An excellent site to answer all your questions and find other letterboxes.

Here are my boxes.  Click on the hyperlinks to read the clues and begin your search.

Traditional Letterboxes
Darmstadt Arts & Literature

Virtual Letterboxes
Charlemagne Virtual
Darmstadt Woods Virtual

Coming Soon...
Frankenstein Castle
Deutsche Marchenstrasse "The German Fairy-Tale Route"
Charlemagne Traditional (Delayed until return in summer, due to bad weather)
Valkenburg (Delayed until return in summer, due to bad weather)