Do you want current production kits or kits that were made but not currently available? In addition to the ones Don mentioned there are these Old kits that I can think of from my limited collection:
From AMT in 1/48 - Stagger wing Beech, Gull wing Stinson, Lockheed Vega on floats and wheels.
From Airfix in 1/72 - DHC Beaver, Otter, Cherokee, Cessna L-19 that can be modified into a 170 (I still want to do that), Beagle Basset, Grumman Widgeon, Short Skyvan .
From ARII in 1/72 - Bonanza, c172 on floats and wheels, c377 Skymaster/O2, Pitts S2, BD microjet / BD-5 combo,
from Matchbox in 1/72 Noorduyn Norseman-floats, wheels, skis, Twin Otter on floats, wheels, skis, Brittan-Norman Islander, Dornier Skyservant.
Italieri - 1/49 Cessna O2 / Skymaster, 1/72 Fokker F-27
A company in Mexico reissue some very old, simple kits - Stinson station wagon?, SeaBee, Bonanza, no windows or interiors.
There are a few more that I can't think of but can look through the pile when I get home from work.