Airbus products can also fly with only 1 winglet out of interest.
In terms of the 777, whilst they don't have winglets, the larger, later versions have raked wingtips (as does the 767-400), which have a similar effect to the winglet, with less weight, however they increase the span which can be a problem on some jets (such as the 737 which uses a smaller gate to the widebodies).
I believe the A340 was originally designed without the winglets, though when the IAE superfan was cancelled they had to add the winglets to compensate for the performance.