This answer has a comment by Pesto which right now is at +91. I am curious as to whether or not there is anything higher than +91 in terms of comments on StackOverflow.
Here is a SEDE query that searches for the highest-scoring comments on a given site. Since it's SEDE, it ignores deleted comments (including comments on deleted posts) and may be up to two months out-of-date.
As things stand (Sep. 2011), the top voted comment on SO with a score of 1215 is:
"sigh . . ...... :<" -Jimmy
On SU, with a score of 328:
"Knowing the answer makes me feel so old..." –Joe
On SF, with a score of 190:
"You have two weeks to deliver him the information, and it takes two weeks to move to somewhere else who can process credit cards. Don't bother - make the decision to move now and abandon the audit." –Scrivener
On Meta, with a score of 353:
"Who the hell is Jon Skeet?" –thenduks
Who the hell is Jon Skeet? – thenduks Apr 21 at 20:37 is currently at 206.
I just found this one and pushed it to 750:
sigh . . ...... :< – Jimmy ↵ Mar 1 at 6:30