Quite a few hacks are already available in Tweakbox
. The problem with it is the unknown scope. Some of the tweaks work only in Samsung stock ROMs, maybe limited to 4.0.3, as they activate or use features of TouchWiz. And for CRT, you even need a patched native library to make it work properly, which is hard to create and can only be exchanged as a whole, no partly patches possible that might work for different devices.
So I'm not sure what's better - many small mods or one bigger collection. If there is something to configure (apart from on/off), each mod would have to include its own configuration screen. On the other hand, bug report handling and releasing new versions is more flexible if you just need to look at one tweak and users don't need to install something they don't need. So yeah.. there are upsides and downsides for both.
There is also a big feature in Tweakbox which has no UI yet, but is working fine if you edit the configuration files directly: Changing DPI and things like that on a per-app basis. I mainly use this to force some Samsung apps to 240 DPI (for which they were hardcoded), while I use a lower DPI for the rest of my phone. I will look into creating a proper UI, but first the framework needs to be cleaned up a little.
And finally, I'm using a battery icon mod via Xposed. That would be a good demonstration of replacing resources and also some kind of template. I don't remember where exactly my icons came from (for credits/approval). I think it was JKay's mod for GB, but I can easily use any other battery mod for the demonstration if I don't find the author.