Over on IT Security we fairly regularly get questions containing a believed-to-be malicious code snippet. The OP is usually a web-admin of some kind and has discovered the snippet on his server, and wants to know what exactly it does.
Some examples; here, here, and here
Is this type of question, given that it is essentially 'could you reverse engineer this for me and tell me what it does', on topic here? They often do involve packing and obfuscation techniques, not just plain readable source.