When trying to install the Cisco ASDM 6.1 on Windows 8 you might get the following error:
Cisco ASDM-IDM Launcher Information
Java Runtime Environment is not installed on this machine. Please install Java Runtime Environment from http://java.sun.com/javase/downloads/
I tried installing several versions of 32 and 64 bit Java and running in compatibility mode. Basically, i settled on using the Java Web Start version, that can be found on the main web portal page. Or it can be launched by using the following link (of course insert your IP address in the first part).
This works fine with Windows 8.