I've already used it. Little case study:
Day 1: I removed half of links on my penalized site.
Day 2: I see jump from 510 to 260.
Day 3: I remove rest of the links.
Day 4: Site jumps to #10. Not bad.
But why not #1 I start to think.
I go to SerpIQ:
What I see?
#1 result has "-2300" links.
Unbuilding links is a new link building.
Good timing by us eh? serpIQ 2.0 now can track negative links. You're welcome.
What... this was serious?