FYI,
Current catch list. Extracted from my database, and all networks looked up manually again this morning for validation of ranges and location.
Some of @iamzippy's ranges were smaller subnets. They are embedded in the below registrations.
They (likely) have more than these, but I have not seen and added them yet.
The European ones are (formally) spread across NL, FR, an IE. Although only Amazon's internal routing can tell where individual pieces are actually being used.
'Amazon_EC2_Asia', '103.4.12.0/22'
'Amazon_EC2_Asia', '103.4.8.0/22'
'Amazon_EC2_N_America', '107.20.0.0/14'
'Amazon_EC2_N_America', '107.22.0.0/16'
'Amazon_EC2_S_America', '122.248.192.0/19'
'Amazon_EC2_N_America', '174.129.0.0/16'
'Amazon_EC2_S_America', '175.41.128.0/19'
'Amazon_EC2_S_America', '175.41.192.0/19'
'Amazon_EC2_Asia', '175.41.224.0/19'
'Amazon_EC2_Europe', '176.32.64.0/21'
'Amazon_EC2_Europe', '176.34.0.0/21'
'Amazon_EC2_S_America', '177.71.128/17'
'Amazon_EC2_N_America', '184.169.128.0/17'
'Amazon_EC2_N_America', '184.72.0.0/15'
'Amazon_EC2_N_America', '204.236.128.0/17'
'Amazon_EC2_N_America', '216.182.224.0/20'
'Amazon_EC2_N_America', '23.20.0.0/14'
'Amazon_EC2_Europe', '46.137.0.0/17'
'Amazon_EC2_Europe', '46.137.128.0/18'
'Amazon_EC2_Europe', '46.137.192.0/21'
'Amazon_EC2_Europe', '46.137.224.0/21'
'Amazon_EC2_Europe', '46.51.192.0/20'
'Amazon_EC2_Europe', '46.51.216.0/21'
'Amazon_EC2_Europe', '46.51.224.0/21'
'Amazon_EC2_N_America', '50.112.0.0/16'
'Amazon_EC2_N_America', '50.16.0.0/14'
'Amazon_EC2_N_America', '67.202.0.0/18'
'Amazon_EC2_N_America', '72.44.32.0/19'
'Amazon_EC2_N_America', '75.101.128.0/17'
'Amazon_EC2_Europe', '79.125.0.0/18'