There are many snowdrop cultivars, conservative estimates are currently at over 2000. Some of them you can already find on the Wiki. For those you find missing; please post your own pictures.
Two websites with a lot of snowdrop cultivar images can be found here:
The official registry with snowdrops cultivars can be found here (many snowdrop cultivars are not officially registered however):
Royal General Bulb Growers’ Association (NL)
Finally an excellent site with a lot of pictures and information is that of the seller Avon Bulbs.