As much as I love geeky necklaces, I know they are not all that wearable. However, there are a handful of normal-looking geeky baubles out there, and I would say that if you were going to rock one, these plastic Camera Necklaces ($10) would do just fine. Kitschy, yes; cheesy, no.
This isn't the first camera necklace I've seen, but some are definitely not adult friendly. I know plastic isn't the most glam of materials, but something about the minty pastels makes them cute and sweet.