  In this article we give a survey on open problems and conjectures concerning
L^2-invariants. We cover the whole portfolio and not only certain aspects as
they are considered in the previous more specialized (and within their scope
more detailed) survey articles [87,89]. Moreover, we include some new results
and problems, which have occurred after these two survey articles were written.
The reader may select a specific topic by looking at the table of contents
below.
