The sabermetric baseball encyclopedia allows you to generate a leader list comparing each players' HR total to the league average over the course of his career.

HOMERUNS                      DIFF  PLAYER LEAGUE
1    Babe Ruth                 602   714    112   
2    Hank Aaron                436   755    319   
3    Jimmie Foxx               387   534    147   
4    Mark McGwire              367   554    187   
5    Willie Mays               367   660    293   
6    Lou Gehrig                359   493    134   
7    Mel Ott                   355   511    156   
8    Mike Schmidt              351   548    197   
9    Harmon Killebrew          345   573    228   
10   Ted Williams              339   521    182   
11   Willie McCovey            317   521    204   
12   Reggie Jackson            315   563    248   
13   Frank Robinson            313   586    273   
14   Mickey Mantle             313   536    223   
15   Willie Stargell           293   475    182   
16   Dave Kingman              290   442    152   
17   Barry Bonds               273   494    221   
18   Ernie Banks               265   512    247   
19   Eddie Mathews             265   512    247   
20   Ken Griffey Jr.           248   438    190