A Marvel license with LEGO would be quite good! Disney owns the rights to Marvel now (I think), so I can imagine that to come soon enough.
I'm not sure if this has been mentioned before, but how about Phineas and Ferb sets?
I have just discovered this wonderful forum! Allow me to introduce myself. I am Neztromia, and I like Hero Factory and Atlantis. My favorite food is pasta, and I am from, Massachusetts, USA. I just simply CANNOT wait to explore this great community!