Ground effect often comes into play. I generally see it as being something which has to be dealt with, rather than being beneficial - sort of like a crosswind.
If you have chosen to carry power into the flare, closing the throttle as you enter ground effect for that aircraft type can have pleasing results, but takes good familiarity with the type. The purist in me says that carrying power down the latter stages of final approach will distract the pilot from learning the feel of that aircraft. Certainly some approaches call for power, usually based on traffic, and the traffic pattern, but don't overlook the benefits in skill development from practicing power off final and flare, when the operating environment permits.
The differences in the response of a type to ground effect are worthy of awareness. Types like a Tomahawk, Ercoupe and light Cherokees react to it, for obvious reasons. This may make bounced landings more common in these types. On the other end of the scale, in a heavy Cessna amphibian on a runway, there is little effect - perhaps part of the reason these types seem to suffer more hard landings.