I know there was years where Barrier Skip was only theoretical in Wind Waker, and eventually folks figured out a way.

I know folks like Pannenkoek (spelling?) probably has folks interested in finding those last few A button challenge skips in SM64 to get the count lower.

Is there a list anywhere of current theoretical skips or other glitches that folks are working on figuring out how to pull off (for all games, not just the two above)? Like a list of "wanted" stuff for folks to work on?

There is no big list of theoretical skips across every single speedgame, because that would be too hard to keep track of. I can tell about a few that are in some of the game I run:

In 60 second burger run, the world records are very optimized, and the strategies used are very difficult. In the last level of the game, you have to travel down a vertical level, jumping on brick blocks as you descend. Each time you bounce on a brick block, you bounce upwards a little bit before falling down, losing about .4 seconds (a huge amount of timesave). Currently, you can make it to the end landing on only two brick blocks, but it's just BARELY not possible to skip the second one. If it could be skipped, it would be huge.

In Tim_, I discovered an infinite height glitch. Unfortunately, it isn't useful in any%. The final boss is located near the start of the game, to the left and high up in the air, so it might theoretically be possible to make it up, but there are walls surrounding it from every angle.