Peer code review is an important part of software development process. It both helps to find defects early and encourages spreading knowledge across a development team.
When adopting code review practices you may want to find a tool that will help developers to organize the code review process: change sets exploration, communicating between developers and reviewers about defects and ways to fix them.
Recently I have done some research on existing code review tools that can integrate with Visual Studio 2010 ALM (Visual Studio 2010 + Team Foundation Server 2010).