(apologies for the resend, my subject was mysteriously stripped from my
first reply) 

I've looked at Ruport before but as far as I can tell, it doesn't really
try to solve the part of the problem I'm most interested in. Ruport
seems to tackle pulling data from a variety of sources in a unified way,
and rendering the output to a variety of formats, but doesn't provide
any help for modelling the reports themselves.

Maybe some concrete examples might help clarify what I'm driving at.
I've writing an interactive system for generating reports on a variety
of different library things - circulation activity, public computer use,
etc. The range of the reports is user-defined - this month, the previous
quarter, etc. The domain (?) of the reports is as well - maybe
system-wide, maybe by region, or by branch, or by individual terminal or
computer. For graphs, the variable in question, etc.

I've taken a few stabs at writing a report model object hierarchy that
encapsulates all this, with varying levels of satisfaction and despair.
I guess this is the sort of thing I'd've hoped that ruport would help
with, even if only by example. I've been meaning to write to the ruport
list for advice about this for a while, but this is as good as
opportunity as any.

- donald