Doing a code review is difficult for me. I don't always think of the design implications because I'm trying t hurry and get back to coding. I have mainly been checking for tests, and functionality. This needs to change and I think I've got some decent steps to help me make the leap, and use some tools to help illustrate my concerns to my coworkers.
A 'golf' score for your code. Anytime code hurts my eyes, flog has a score that backs up my thoughts. Even without the developer knowing how things are being scored numbers seem to work for us.
Points out OO Design principle issues. I haven't used this much, but the few test runs I tried came up with some good suggestions. Really you should just check out the docs for all the things Roodi does.
Ruby code smell detector. Reek looks for a lot of common code smells and is easily configureable.
I hope that by bringing a new approach to code reviews I can improve our product, team morale, and the skills of everyone involved. I will keep you posted on how my toolbox works out. I'd also welcome any suggestions on source about improving code reviews and/or tools like the above that help focus where I need to spend the most time reviewing.