Read up a bit of Fetish and **** and casually bring it up next time you meet.
http://dmoz.org/Adult/Society/Sexuality/Activities_and_Practices/****/Activities_and_Practices/Bondage/ is a good place to start (hope the URL doesn't get mangled by this board)
Say something like "Have you tried any Nawa Shibari lately?"
This is a form of Japanese Rope Bondage.
When she says "no" then you can explain how it differs from other techniques.
When you're finished explaining it, drop the subject and move onto something much more innocent.
She'll be wondering "Why the heck does he know all this - maybe he's just as kinky as I am?"
Next time you see her, she'll be bursting to discuss it with you further and once she knows it really interests you too, she'll more than likely want someone to experiment with. Or if you're lucky, she may decide then and there to try - she's obviously testing the waters with you on the matter.
If that's where her interest lies then you need to raise her Interest Level with you in regards to that side of things - you know what she's into - now make her putty in your hands by showing her you know what she's talking about and impress her with the fact you know more about it than she does.
Just my $0.02.
