Atomic mass of Copper-63? This URL lists the mass of Copper-63 as 62.9295975(6) and this other URL lists the mass as 62.939598.  These values differ by almost exactly 0.01 which seems hard to explain by experimental error.  Why is it that these values differ in a significant digit but have the same less-significant digits?  Is one of them a typo of the other?  What is the correct value?  What is the origin of both of these values?
This discrepancy was noted by commentators in this article about a supposed cold-fusion reactor.  According to those commentators, this value is relevant to the cold-fusion debate because it makes all the difference as to whether or not the supposed reaction is energetically feasible.  The linked article concerns the same cold-fusion claim discussed in this previous physics.SE question.
EDIT: user9325, voix, and user3673 have indicated that the correct answer is 62.929...  I have started a bounty on the origin of both the correct and incorrect values.
 A: Since both references give the same percentages and the same overall atomic weight, an easy calculation shows that this only works out for the number in the first link, therefore the second decimal should be 2.
(And I think it would be nice to contact the webmasters of the second link.)
A: The 2003 Atomic Mass Evaluation:
Cu(63) -  62.929597474
The 1995 Update to Atomic Mass Evaluation:
Cu(63) - 62.929601079
The 1993 Update to Atomic Mass Evaluation:
Cu(63) - 62.929600748
A: I've started a discussion on this at the Wikipedia article.
If I had to guess at the origin of this discrepancy it is a typo in one of the old CRC's where someone typed '3' instead of the correct digit of '2'.  If that's the case there may have been merely an internal memo correcting the typo -- if that.
A: Okay, so I did some poking around and the 66th-75th editions of the CRC Handbook of Chemistry and Physics all have the incorrect atomic mass of Cu-63 [62.939598], and from 76th edition on they seem to have figured it out. 
Those isotope mass tables are put together from a number of sources, so it's hard (time consuming) to tell exactly where the error came from. I did notice however that starting in the 76th edition of the CRC, where they get it right, they start citing G. Audi and A.H. Wapstra, "The 1993 atomic mass evaluation", Nuc. Phys. A 565 (1993) 1-65. In editions 66-75, they were citing Audi and Wapstra's "The 1983 atomic mass table" which appeared in Nuc. Phys 432, 1 (1985). 
Now, I looked at the 1993 version, and it has the correct 62.929.. mass, but I have not been able to find Wapstra and Audi's 1983 version of the same table, so I don't know if it was one error by the CRC which got carried over year after year, or if 62.939.. is in fact the value given in that paper. 
I did find at least one piece of evidence which points to an error by the editors of the CRC in the 2nd edition of the Encyclopedia of Physics [Lerner and Trigg, 1991]. Their table of isotopes lists the correct 62.929... value and also cites Wapstra and Audi's 1983 paper. 
I hope that satisfies everyone's curiosity, because I don't think I can do any better then that. ;-)
