A little something I came up with over the weekend. It's sah~, but based on the difference between the input and the current sampled value. Works well as a vibrato remover, etc. You can also specify a minimum time between samples (e.g. no faster than every 80 ms)
I'm posting this in my toolbox for more permanent reference, but since there's a bit of lag with that, figured I'd post it here, too.