Is this normal!?
Upon visiting the negative reputation profiles a positive reputation has been displayed.
About Opera Version information Version 11.10
System Windows 7
I think that'll be bounties.
I definitely saw jldugger put a 500 bounty on this question, and quickly clicking through some of the others, they look like bounties as well.
You can go on a users profile, go to the reputation page and click the huge negative bar in the chart and that will reveal a bounty was offered.