Flashstuffer can perform FIVE types of cookie-stuffing:
Forum stuffing - and YES, it can even blank the referrer!
Own page stuffing - stuff cookies using Flash on your own pages, almost impossible to detect. Can even spoof the referrer!
3rd party page stuffing - stuff cookies on other websites that allow you to embed Flash! Can also send a spoofed referrer.
Favicon stuffing - a little known stuffing technique that doesn't require ANY cookie-stuffing code on your page...even sends a blank referrer!
Mobile stuffing (BETA) - stuff mobile devices (cellphones, tablets) without Flash.