Cut out taxying under power.
Proposals by Governor of California Arnold Schwarzenegger and Virgin Atlantic's Richard Branson suggest that airliners should be TOWED to runway thresholds to avoid burning aviation fuel (often said to be up to and beyond an hour) whilst taxying from the stand.
This is aimed at reducing the 'global warming' effects of 'greenhouse gases emissions'.
The idea seems to have some merit, as taxying fuel allowances could be omitted (or reduced) and overall fuel loads reduced.