[R] pretty for date-time?

[davidr@rhotrading.com]

pretty() works well for numbers and axTicks() can help for potting log axes, 
but has anyone written a pretty for chron objects (or other date or date-time classes)?
It would have natural units of years, months, .., days, hours, (minutes?), and
it would choose the appropriate unit based on the date(time) range.
I have searched the archives and documentation to no avail.
(I wrote one of these back in my Fortran days, and it was non-trivial, even just for dates.)

If no-one has done it, I would be willing to work with someone more expert on production quality R to produce it.

Thanks for any pointers,

David L. Reiner
 
Rho Trading
440 S. LaSalle St.
Chicago  IL  60605
312-362-4963
