Transport Canada worked with Air Transat on on fuel usage reduction.They didn't use particularly 'sexy' methods to do so, but still worth a read.
Aircraft Fuel Reduction Initiatives - Transport Canada
Take a look at the 787’s electrical architecture. Bleed air and hydraulic power sources replaced by electrically powered compressors and pumps. The 787's engines use electrical ‘bleedless’ systems, eliminating 'hot' air ducting .