I believe at one point I've seen online some sort of appendix where you can look up a particular phoneme, for example, and see how it either develops in certain languages, triggers some form of sound change in languages, or what it evolves into.
This is a very cool resource, but for the life of me I can't find it again. Does anybody know anything similar to this? (It doesn't have to be exactly the same website, just anything that has a similar function).