Occasionally I write Capture The Flag challenges, some of them will end up here.
2Cereal - A crypto challenge based off the CSAW 2017's 'serial'.
flag-colours - A crypto/misc challenge of my own design.
zucced - A web challenge with a memeingful Zuckerberg theme. (Theme can be modified easily)
Feel free to use them, change them, contribute to them; but be aware that solutions are publicly available here (I'll often try to write fairly generic solver scripts too that might defeat trivial changes to the challenges themselves).