Is there any one source that has a collection of all of these? or many of these? I did a quick google search and did not see any one list/rules. A lot of websites, but is there on that just lists the hexagonal variants and the rules? thanks.
HexDame has been mentioned. You can find more about it on Christian Freeling's website. Another game is Pskov Checkers from Russia. It works like Russian Checkers, just with the board and setup described. The promotion area is the opposite corner, one field only. Both sources claim that their game is more tactically interesting than standard Checkers. Freeling adds that the endgames are less drawish as well.
Other variants have been designed. If the flat side of the Hexagon points towards the players - as opposed to the variants above -, rumor has it that they do not work.
According to the Russian source, Pskov Checkers is like Russian Checkers, but with a hexagonal board. A link for Russian Checkers has already been provided, here it is is again: Shashki.
Shashki is similar to International Checkers in so far as men can capture backwards and kings are long range. The differences to International Checkers are: capture is forced, but it need not be maximum capture, and there is promotion within a capturing move.
I assume Pskov Checkers works mostly like Hexdame. Differences are: the setup is as in the diagrams, promotion area is the distant corner only, no maximum capture, and promotion within a capture.