File search question

[Mark Carroll <mark@chaos.x-philes.com>]

Just wondering, is there a way to get a list of all the files on the
system that:

(a) Aren't "owned" by any installed packages

(b) Differ from any default provided by a package

...?

I guess that (b) would be impossible without consulting the original
.deb's, unless the system stores md5sums or something for all owned files.

-- Mark