Kristi Hines is a freelance writer, ghostwriter, and copywriter in Phoenix, AZ who develops blog content, ebooks, emails, lead magnets, and website copy for marketing agencies, B2B, and SaaS. Contact Kristi directly at http://kristihines.com
I would set up conversion tracking for your sign up form in Google Analytics, and then analyze the amount of traffic you receive from SlideShare to your website that leads to sign ups.