Agreed, documentation is definitely needed. I realize some features are not self-explanatory or not properly advertised -- proof is that some features already present in muCommander are often requested in the forums.
A reasonable first step would be to have a Wiki and populate it with the existing documentation scattered across the forums, and go from there. As a matter of fact, setting up a Wiki has been on my todo for a while now. If some of you guys are willing to contribute some documentation, I'll definitely prioritize this task.
Regarding the in-application documentation, I was considering having contextual help buttons that would link back to the Wiki. Here's a mockup to illustrate :

- help_mockup.png (25.27 KiB) Viewed 4074 times
This would allow the documentation to be centralized on the wiki and minimize the application-specific work. On the downside, that means help would require an internet access, but that's a fair tradeoff I guess.
In addition to that, some 'Tips of the day' could be displayed on startup to advertise some of the less visible features and teach the user a trick or two.
Do you have any opinion about this ?
Maxence