Asynchronous reviewing software systems really help. I've found that when things get busy, they get busy for different people at different times, and it can be hard to get the full value of somebody's attention when they're in the pressure cooker.

I really enjoyed using Code Collaborator on a recent project, as the flow was more compatible with everybody's schedule throughout the project. I could do a commit, select a reviewer (or reviewers), and an email would be generated with a link. When the reviewer HAS TIME, they can log in to the system, see what the review queue has for them, and let them get to the meat of the differences, leaving comments/questions in the system as meta-data (NOT the all-too-standard in-the-code /* what is this never initialized?!?! */ comment). When I in turn log in (when I HAVE TIME), I can see this feedback, and if I comment further, the dialog is scoped right at the change. If I do a follow-up commit, Code Collaborator was good at maintaining the dialog for the new differences...

In any case, I found the system to be valuable, and a lot of it seemed to be the asynchronous nature of it. Not having to schedule meetings was key.