Here's the all-time list as of the start of the 2008 season:
CAREER
AT BATS >= 500
AVERAGE AVG AB
1 Larry Walker .334 4076
2 Todd Helton .332 5663
3 Jeff Cirillo .320 1126
4 Matt Holliday .319 2117
5 Todd Hollandsworth .318 582
6 Andres Galarraga .316 2667
7 Dante Bichette .316 4050
8 Darryl Hamilton .315 531
9 Jay Payton .309 770
10 Juan Pierre .308 1409
11 Ellis Burks .306 1821
12 Mike Kingery .306 651
13 Garrett Atkins .302 1823
14 Kaz Matsui .300 523
15 Charlie Hayes .298 996
16 Eric Young .295 2120
17 Vinny Castilla .294 4099
18 Quinton McCracken .291 609
19 Aaron Miles .288 846
20 Jeff Reed .286 962
21 Troy Tulowitzki .284 705
22 Luis Gonzalez .283 875
23 Jeromy Burnitz .283 540
24 Terry Shumpert .282 1027
25 Brad Hawpe .282 1425
26 Neifi Perez .282 2728
27 Cory Sullivan .281 904
28 Royce Clayton .279 574
29 Jamey Carroll .275 690
30 Mike Lansing .274 1094
31 Joe Girardi .274 1102
32 Todd Zeile .273 506
33 Preston Wilson .269 1069
34 Walt Weiss .266 1760
35 Ben Petrick .264 549
36 John Vander Wal .262 558
37 Juan Uribe .258 1155
38 Yorvit Torrealba .252 619
39 Clint Barmes .252 961
40 Greg Norton .252 572
41 Brent Butler .248 553
42 Kirt Manwaring .247 765
43 Jason Bates .239 677
44 Charles Johnson .233 661
Babe Ruth's career batting average was .342.
Ivan Rodriguez has a career batting average of .298.
Wade Boggs had a career batting average of .328 and Don Mattingly had a career batting average of .307.
As of 2009 Robinson Cano has a career batting average of .306
Keith Hernandez had a career batting average of .296. He had 2,182 career hits in 7,370 career at bats.
Babe Ruth had a career batting average of .342 with 8,398 at bats.
Willie Mays had a career batting average of .302, 3,283 hits in 10,881 at bats.
Through August 12, 2016, Alex Rodriguez has a career batting average of .295.
Sammy Sosa had a career batting average of .273.
Hank Aaron had a career batting average of .305 (3,771 base hits in 12,364 at bats).
Pete Rose's career batting average was .303 (4,256 base hits on 14,053 at bats).
Ty cobb has the highest career batting average at .366