Yes, they exist! Speed strips for .44 Spl/Mag
And they also work for .45 and they say even .410 Shotshell! They actually call them "Quick Strips" (I suspect there are trademark issues with "Speed Strips").
The Quick Strips I ordered from Tuff Products showed up yesterday. I like these a lot, I need to practice loading with them a bunch, but way easier to carry than another speed loader (I'll probably go with one speed loader and the two strips).
We've had a couple threads on these here recently (I started one). Seemed no one could find such an animal, and many of us were searching for them. I suspect these are a new product, as HeadHunter mentioned seeing them at the Shot Show this year in this thread (Thanks!). Shown here with my Charter Arms .44Spl. Bulldog Pug, an HKS Speedloader and a Mika Pocket Holster.