I need to represent data within a column (or at least I think I do)
in a manner akin to master/detail. Specifically, I want to describe
a row thusly:

Column1 (text)
Column2 (text)
Column3 (user/group)
Column4 (complex data type)

The definition of column four would be like a "sub list" like this:

Field1 (text); Field2 (text); Field3 (text);

Essentially this is a hierarchical dataset in a list. It seems to me
that this should be doable since Lists are XML Schema defined, but so
far I've not found a clear way to approach a solution.

Alternatively, I would be completely happy with representing the
content of column four as a delimited text field ASSUMING I could
create a custom form that would unparse and reparse the data during
user entry/editing. I'm adept at ASP.Net, but I'm not sure how to
create an ASP.Net page that can coexist and feed/maintain the
sharepoint list though.

The specifics of what I'm trying to accomplish are that I've been
asked to create a workflow that allows department heads and the like
(special users, but not Collection Admins) to create the definition
of an audience that will then be workflowed, approved, and (assuming
all is approved) made in to an audience at the end of the process.
Unfortunately, I created a console application to prove to myself
that I could programmatically create an audience fairly easily, and
failed to think about how I'd feed that event... the form/list
creation has proven to be a major stumbling block.

What I'm hoping for is just a "don't do it this way" or "you're
making it too complicated" or... worst case scenario... "it's gonna
be a pita, just slog it out".