[codinghorror]

Also font and alignment issues cross browser can be brutal. There is a lot to be said for a tiny image that works everywhere, on any device.

[qopp]

What about an svg?

[other_herbert]

That wont work in email... I'm generating a usage graph (svg) that is emailed and the graph will not display in the client.. Must be opened in a browser

[ZeroGravitas]

Seems like you could use an SVG avatar for clients that can handle it and fallback to PNG for email.