Firestorm
I did my best, I have no regrets!
Yours will all probably be more interesting than mine as all I really use last.fm for is free internet radio (combined with 6GB/mo data on an iPhone it's friggin' great).
How to do this yourself:
1) Go here and type in your last.fm username. Click Generate.
2) Copy the text and paste it in the text box here.
3) Set the text to half and half or something under edit so it isn't all ugly and diagonal.
4) Hit PrtScr on your PC (whatever screenshot is on Mac/Linux), paste it in an image editting program and export a cropped version of just the picture as .gif or .png (not .jpg which will make this uglier).
5) Upload it here.
6) Post it in this topic.
Edit: I take it back about the iPhone app being great. Apparently as of yesterday they've stopped serving Canadians. God I fucking hate the music industry.