Oops! You did say BIGGEST sponsors, and this is the BIGGEST I could find:
Code:
http://refer.ccbill.com/cgi-bin/clicks.cgi?CA=934908-0000&PA=1855956&HTML=http://www.asiancockstars.com/webmasters/webmasters.html
131 characters in the referring URL - to me, that's BIG!