Thinkgeek has posted a pair of spinning fidget rings for gamers: a $20 D20 ring you flick to get a value between 1-20, and a $25 “counter ring” that clicks from values between 0-99, useful for tracking hit points.
Both are stainless steel, available in black or rainbow, with chip-resistant numbers painted in PVD. My wife and I had custom cipher wheel rings made for our wedding, designed by Bruce Schneier and made by Isobel Rucker, with a prizewinning cipher by Chris Smith. Having worn a fidget ring since 2008, I can attest that they’re enormous fun.