Thought an array of the new Intel extreme 6 cores arrayed against a piece of bread could have been a contender. ?If it's Amazon then you absolutely can link it because OcUK don't sell toasters.
seriously - the Breville type ones with the two wide slots where you can lay the bread down sideways, and rotate it at half time do a good job.
You also need reasonable bread with uniform moisture content, I find that homemade bread often comes up most uniform.
Quick google also shows a couple of transparant walled toaster to put on next years xmas list eg - one up on the daft transparent kettle idea ?