Here's a short list:
1) Shorter intervals between logging of samples, especially for those channels with high update rates, i.e. wind, temperature, rain. This may require separate log files.
2) Additional channels and intervals for custom charts, especially monthly and yearly statistics.
3) Ability to control the precision of statistics, e.g. allowing all averages to be formatted to four decimal places, etc.
4) Statistics from the weather station itself (or sensors), e.g. Vantage data logger interval, battery status, console voltage, etc.
5) Automatic membership into the WIKI upon registration in the Forum, i.e. enable the transfer of knowledge to the WIKI