Browser Fingerprinting - digging further into the client

I previously wrote about some techniques for Browser Fingerprinting (or "Device Identification" as it's known in some circles). Today I came across an interesting technique already in widespread use which detects variations between devices by looking at how content is rendered by WebGL / HTML5 Canvas.

Typically as much of the processing for these as possible is pushed onto the underlying hardware, resulting in consistent results for a given device independently of the OS / software. There is a surprising amount of variation here. However there's not sufficient variation for it to be used in isolation from other methods.

Update: 28 Jan 2015

Another interesting article found here lists Google Gears detection and MSIE security Policy as enumerable interfaces for fingerprinting. (The TCP/IP parameters is presumably done serverside, while proxy detection uses Flash). But the really interesting bit is that 2 of the products tested tried to hookup with spyware on the client!