Thanks for the comments. I created gzipWTF after being frustrated with not having an easy way to check for it. There was the Yslow firebug plugin, but that required some installing, and still I had to dig through to find out about gzipping.
I agree this would be useful as a browser extension, but I wanted to make it more accessible to simply anyone. There is an underlying goal of raising awareness of the importance of site speed.
I'm very happy and humbled to see people are finding this a useful tool, and will be doing my best to update it with future releases. We're also working on a possible paid version that will include an api. Perhaps another developer looking to help build an extension could leverage this?
Tyler/
gzipWTF
