I have a Captivate and Kindle Fire sitting around that I wanted to jump up to Jelly Bean for quite a while. Tonight I decided to take that leap. The Captivate was running CM9 previously so I just did was download CM10 and Google Apps for JB onto the phone, and then proceeded to do a Factory wipe and load CM10.
I don't use the Captivate anymore as a daily driver but I am pleased by the speed/smoothness that CM10 brought to the plate. It is currently running 4.1.2, and with the new CM10 nightlies they added the ability to download and update your system right from the android settings. I plan to use this as an IP phone with Groove IP, and will see how that works for the near future.
My second device was the Kindle Fire, this also was running some modded version of CM9 for a while. Again wanting the newest and greatest I set out looking for CM10 or some variant for the Fire. I found one dev by Hashcode who was doing the Kernel work on the fire, and have been following his release's for a little while.
The other day I upgraded to HashCode's CM10 variant for the fire, and it also shows a smoothness that was not present in the original Fire. This rom is not able to be downloaded directly through the settings page as the Captivate, but its not hard either. Just have to go to a different website and download the rom. Once again you also need the Google Apps for Jelly Bean. The install was pretty much identical to the Captivate, so no use restating.
My current daily driver is the Samsung Galaxy S III and I have kept it rom free for about a month now, but getting that itch to install CM10. I keep saying to myself Jelly Bean will be out shortly for the S3, and then everything will be fine. More then likely even when JB comes out for the phone if I have not already updated it to CM10, it will be shortly there after.