Side-by-side diffuser tests

There seems to be a lot of misinformation and uncertainty when it comes to flash diffusers. It's commonplace to hear people testify about the merits of one diffuser over another, but it's rare to see actual side-by-side comparisons that definitively detail the resulting picture from each apparatus. I've tried to do this with the flash I own, but I do not own any off-the-shelf products for comparison, so I was limited to the homemade variety. Does anyone have a link to a good comparison of flash diffusers?

The default answer seems to be, "get a lightsphere," but I've heard enough recommendations; I'm ready for some solid test results.