I wanted to mess about with the lighting in order to get a blue effect going as the Yammer logo is on a blue background, so I set up my camera to white balance for a red gel I held in front of the lens as a test shot. I then gelled two flashes (key and fill) red and gelled a third (back / hair light) blue.
I used the Sigma 15mm 2.8 fisheye for most pictures and had the Canon 50mm 1.4 on for some more standard angles. All shots were pretty much taken at f/3.5, 1/200s and ISO 400. They were taken in RAW and looked great on the camera screen when rendered, however Lightroom was not able to process them the way I had shot them - I didn't realize that Lightroom's interpretation of Canon RAW is not perfect and thus I had to mess about a lot with the settings until I got something that I wanted to keep.
Anyway, had some fun taking them and luckily it seems everyone is happy with their new profile pics! Here are a couple of them: