One of the features that I really like about the UM extensions is the ability to combine together event-business logic. Given that any real-life application (like ZoomFlex) has quite a few commands, having a separate Command class for each command can become quite overwhelming. The ability to aggregate command logic into context-specific command classes is very useful.
I’ll post links to these over the next few weeks. In the meantime, if you want to have a play with doing that, feel free to check out these apps from Google Code, and drop me a line (at indy [at] nagpals.com) so that I can set you up to commit changes back in.