I am a massive, and unashamed CyanogenMod fanboy. Sure, other ROMS offer more settings (AOKP), or are super fast (CodenameAndroid), but both these ROMS have their issues. I find that AOKP’s settings aren’t as elegantly-incorporated into Android as CM, nor is it as smooth; and despite its speed, I found that CodenameAndroid was just not stable enough for my liking on my Nexus S.
CyanogenMod is just awesome. It’s fast, it has a stack of useful features that aren’t clumped together in an incoherent mass of toggles and it supports pretty much any device you can imagine, with pretty awesome stability. So, because of my fanboism, I try to keep up with the latest and greatest nightly builds. The recent CM Updater made it a lot easier to stay current, but it disappointed me that you still needed to download the full 200 (ish) MB zip file every day. This is where CyanDelta steps in, and it is absolutely the greatest thing to happen to Android customisation since the ClockworkMod recovery (which is not unlike the sliced bread of the Android world).
CyanDelta takes the zip file for your most recent nightly update, works some dark magic, and somehow gains the ability to check releases on get.cm against the zip file you fed it to determine what exactly has changed between your current release and the newest nightly. It then downloads only the difference, which works out to be a file of about 5 – 10 MB. It then works from this delta file in future to determine what needs to be downloaded to keep your build current.
There are a few neat tricks as well – it can check for updates at prescribed intervals (polling only, not push notifications unfortunately), which can be disabled once the battery level falls below a certain point. The application also has the ability to be programmed to install custom zip files after updating, to save you the bother of rebooting again to install custom kernels or other tweaks.
The application is free, but ad-supported, and you can donate to remove ads if you’re that way inclined. It only works on official CyanogenMod builds that you can download from get.cm, and requires TWRP or ClockworkMod-based recoveries.