Sumthin Fishy

I don't have any RCS yet, but I'm planning to set up a shrimp bowl like this very soon, so this is a problem I'll be having also. (Thanks for the idea, btw!) According to most sites, RCS are very cold tolerant and can even be kept in outdoor ponds as long as they don't freeze over. The profile on Petshrimp.com says:

These animals also display a wide range of temperature tolerance. My shrimp were kept at temperatures between 50°F and 86°F and were eating even at the 50°F mark. Others report that they have kept these shrimp in garden ponds in frost free environments where the Red Cherries were able to withstand temperatures in the 30s°F. Breeding, however, seems to only take place at temperatures of 68°F and above.

But if you wanted to keep them warmer and more active, you could try the Hydor Mini Heater. It's specified for 2.5g minimum, but judging from the comments about them on various sites, some people use them in 1 gallon bowls with no problem. I imagine if it got too warm, you could position it only partially submerged or place it under the bowl or maybe put the bowl in a cooler location.

Just some thoughts...