Oh, come on, this list is still full: <a href="http:&#x2F;&#x2F;www.claymath.org&#x2F;millennium-problems" rel="nofollow">http:&#x2F;&#x2F;www.claymath.org&#x2F;millennium-problems</a><p>:)<p>If you need help picking, I&#x27;m definitely going to go with P =? NP. That seems likely to keep you busy for a long time....