I've been playing around occasionally with using Rietveld (codereview.appspot.com) for doing OpenBSD code reviews and have written up some rough notes on how to use it at https://github.com/mdempsky/openbsd-stuff/blob/master/notes/codereview.txt. (Feedback and suggestions welcome!)
As a quick example, a few weeks ago I refactored how the wdc channel_queue structure is allocated and uploaded the diffs at http://codereview.appspot.com/4521049/. As a more thorough example (including comments), I uploaded at http://codereview.appspot.com/4279046/ all of the diffs exchanged by deraadt@ and I when we were working on switching the SCSI stack to use dma_alloc(). IMO, the two most useful features of this are: 1. Being able to look at just what changed between successive iterations of a diff. For large diffs, it's frustrating to have to completely re-review the diff when only a few bits changed. 2. Being able to comment inline and also see those comments when reviewing subsequent versions. In the SCSI example, you can find a few places where comments were made on issues in the code, but because they only happened on icb, sometimes the comments were overlooked and didn't get acted on until the issues were noticed again the next time the diff was fully re-reviewed. I find the keyboard bindings (n/p for moving between hunks; j/k for moving between files) and the side-by-side views nice too. (You can also always download the original raw diff if you prefer that.) Anyway, I just wanted to suggest people check it out.
