She posed naked on horseback for Forbes to promote animal rights in 1997.
A ultra low resolution reproduction of the image can be found at: rohitnair.wordpress.com/2011/12/13/cisco-history-cisco-systems-history-and-trivia-brand-history-and-trivia/
She's kind of lying on top of the horse's back, and you can't see much, just some tastefully light erotica. It's not like she's fucking the horse or anything.