Answer by  
                                                                                          Maiasaura (27)
                                                            
                          
                          
                                                          Yes, I am sure there are many such lists.  The Clay Mathematics Institute has a list of what it calls Millennium Problems--unsolved, important math problems for which prizes are offered.  These are just a few of the unsolved problems, but they are considered very significant.  I imagine Wikipedia might also provide a list.