So, does everyone here know there is actually a pretty slick web-based game for these things? My 9 year-old is now all into playing that. It is a lot like Club Penguin that he was really into about a year ago - but there's no "premium content" monthly fee. And you can use the portal (any of them) with the computer to get them into the web game (this must be why the 3DS version comes with a USB cable). I'm not talking about the PC/Mac version of the game here - it is an actual web site game that has some pretty nice minigames and such. And it is the only version with any sort of online component. You can see other people's Skylanders running around in the hub world, create a friend's list, chat, etc.
I mean, this is just gravy on top of the whole experience and definitely adds replay and more to do with the figures. You know those codes that come with the figures? Well, I only tried one of those and it told me it was invalid. But since you can just drop the fig on a portal (after installing a driver for it) they aren't necessary anyway. The figure keeps both its console adventure and online game stats (both of which you can view on the site). Even if you have no figures, they give you a few to start with so anyone can get into the web game. It is nothing mind-blowing of course, but a fun diversion for kids and a way for my son not to tie up the TV yet still get to play with his Skylanders
You can even register all the Adventure pack pieces (even the Volcanic Vault) on the web-based game though I don't think they do anything besides maybe get added to your collection.