Note: This is stuff not being written by Millar, so there ya go. ;)
Spider-Man vs. Cap is just gut wrenching, on some level.
Ben Grimm standing against hero registration.
Thunderbolts being used to hunt down heroes? PERFECT way to tie in the TBolts.
The GLA pop up in Cable/Deadpool, where 'Poolboy is doing much the same as the Thunderbolts (And both books are by Fabes. Hmm...) Meanwhile Cable is keeping himself above the fray...
And Quicksilver turns up in X-Factor, finally.
Just lots of cool stuff. Not all so much directly part of Civil War, but having these events happening during the event elevates the books that are part of it to being good reads, although most of these are some of my favourite comic writers, so go figure. ;)