I had an idea to write one test fixture per feature.
This isn't quite the same as one fixture per method, but
it's similar.
Another idea I had is to write one fixture for each of a
class's interfaces. That way, the tests are written from
the perspective of a particular set of clients (the ones
that use that interface).
I haven't tried either of these approaches yet, so I
don't know whether they help in practice.
In any case, I do like your idea because it makes
fixture names more meaningful.