The Typesafe Callback Framework for C++. allows you to define signals and to connect those signals to any callback function, either global or a member function, regardless of whether it is static or virtual.
J. Schulte, T. Hampel, M. Gießmann, F. Ferber, and K. Stark. DeLFI 2008: Die 6. e-Learning Fachtagung Informatik, 978-3-88579-226-0, page 101--112. Gesellschaft für Informatik e.V. (GI), Silke Seehusen and Ulrike Lucke and Stefan Fischer, (September 2008)