On the clueless usage page, where it shows the units used for each rate for the current month (Christmas, daytime, evening, Holiday, night, weekend, night special), either highlight the current rate that is being metered or add a separate line which simply states which metering rate is currently being applied.
This is no big show stopper but it can be useful over the Christmas period since there is a large mix of different rates happening during that week, from peak-time to Holiday rate, days of no rate at all, etc etc. It would be nice to login and just see which rate is currently active on the broadband connection.
Showing this on the clueless graphs may also be of benefit (as has already been suggested by other customers).