The below listed challenges were coded for Win 9x/2k and may not work on current Windows versions.
ReTrace - KeyGenMe.
Re-Venge - Revenge Crackme.
KeyMe - Keyfile crackme.
Crackhead - Older crackme.
CruddMe3 - My third crackme and my first one written entirly in win32asm. Has 3 levels with different challenges