http://de.logiflash.com/workbench.php
Online-Logiksimulator für digitale Schaltungen mit europäischen Normsymbolen. Leider auf Flash-Basis.
LogiFlash is a Flash logic simulator with many logic components (gates, latches, flipflops, multiplexers etc). You can create your own components, use an oscilloscope to trace signals and create exercises to be solved.