I haven't got any links available at the moment, but a good tip is to add 'png' or 'svg' to your Google search.
For example, if I do a search for 'Red Bull logo' (without the quotes), the first Google Image result is one with a non-transparent background.
But, if I do a search for 'Red Bull logo svg' (without quotes), the first Google Image result is the SVG from the Red Bull page on Wikipedia.
F1 Graphics Swapper ---
Lensdump - Renders and Screenshots ---
GP4 Performance Generator