OK, I'll start this off with my project this morning. As a drum maker producing high gloss finishes, I do a LOT -- I repeat, a LOT -- of wet sanding by hand on curved surfaces. I've searched for flexible sanding blocks but wasn't able to find anything that satisfied my basic criteria: (1) have enough thickness to get a good grip on, especially finger/thumb slots, (2) include some sort of clip capability to hold the paper without having to use PSA or hook'n'loop, (3) survive being wet on a regular basis, and (4) accept sandpaper strips from a 9x11 sheet in the interest of economy.
So I took one of my oldest Rockler soft rubber blocks, clamped it to a secured piece of scrap wood, and made 6 or 7 cuts into it with a jigsaw -- deep enough to allow easy bending under very light pressure, but not deep enough to encourage tearing apart down the road.
Works like a charm. And no, that's not how I actually hold it during use.
OK, JeffH is our only entry that included pictures so is the winner by default. Jeff, please contact our new Treasurer Michael Mathews to collect your $25 prize.