Reminds me of this old ad for a "bug finder" on getacoder, available as a PDF since the original is gone: http://blog.willbenton.com/wp-content/uploads/2008/11/bug-fi...

    The purpose of this project is to create a debugger program.
    This program will take as input the source code another
    program, and will analyze that other program and determine 
    if it will run to completion, or have an error, or go into 
    an infinite loop.
    
    To state that another way, given a function f and input x,
    determine if f(x) will halt.

I'd personally go with BestCoders, $500 and 10 days is a pretty good deal!

It's only WTF if the bounty demands Polynomial time :-)