Most cases I would go with "on our website" But something for a seductive site I would go with "in our website" Like a hot blonde woman in a skimpy uncomfortable uniform would say "Come have a look in our website…"
Avery, you cheeky devil I'll go with that, though... 'On' is most often appropriate, but 'in' and even 'at' and 'to' would be acceptable depending on usage and context.