For example, Neal Stephenson's handwritten manuscript for The Baroque Cycle is a four-foot-tall stack of fountain pens and paper (I still haven't gotten into book three yet). That was surprising. There were several replicas of Star Wars and Star Trek props and characters, with a few real props mixed in. This was a bit disappointing, because what's the point of having a resin replica of Yoda? It's kind of neat on its own, but replicating the late 90's experience of going to a WOTC store wasn't what I was expecting.
The biggest oversight, IMHO: There's the Jetsons. There's Galaxy Quest. There's X-Files. But there's no Doctor Who.*
Granted, I know that most of their collection is based on loans from private collections, and perhaps there's only one collector of Doctor Who stuff out there, and he won't be around for another five years.
* OK, there's one 3"x4" black and white photo of four daleks and Tom Baker, buried in a timeline on a 30-foot-long wall.