<p>Which is the best way to display a custom form for each new document being added to a specific document library?</p>

<p>I want the user to have some control over some actions that adding the document will cause - specifically, tasks created for users in a Task List, which the contributing user will have to OK before committing.  </p>

<p>Is the best way to do this via a Workflow or an event handler?</p>

<p>Regards
Moo</p>

I don't know how well it works with the CD/DVD distribution front, but the first thing that comes to mind is
Gears
. On the .NET side of the fence there's
Silverlight 2
. Then there's the
Mozilla Prism
project, although I don't know how far advanced that is.
These are all designed for not just offline access, but mixed offline/online, talking to a server when it's available and working locally when necessary.