[Edit: WPS is broken and should be disabled on all routers that support it according to SANS.]
Guest networking is another cool feature on some routers. It is a separate SSID for, well, guests to use your WiFi from. It is isolated from your main network so that guests won't have access to, for example, your network attached printer or to your media collection you stream from your laptop to your television. This is just so cool for people who may be sharing their Internet connection with their neighbours or roommates but just don't want their surfing habbits to infect their own systems :)
And the USB ports. Many routers seem to have one or two USB ports on them which is interesting, but what's more interesting is what you can do with them. A lot of new routers have built-in file servers so as soon as you attach some storage, you can share files and folders from it to the PCs on your network. How convenient is that? Some routers have more sophisticated web interfaces than others and let you specify which folders are or aren't shared - but either way, if you're buying a new WiFi router anyhow and you get this feature, it means you get a functional NAS for the cost of a USB key or USB attached hard drive! *And* some routers are starting to come out with USB 3 - SuperSpeed USB which if you consider these routers have not only 802.11n speed on the WiFi but also Gigabit speed for the network ports, is an awesome feature.
And that's not the only thing you can do with the USB port - some routers will also act as a print server! So you attach your generic USB printer to the router, and it's now a network printer you can print to from any laptop or PC in the house. Talk about great value-added feature! I love it!
And did I mention that new routers are all now wireless N with Gigabit LAN interfaces? WiFi is still garbage and a ways away from being reliable outside very small deployments, but N is an improvement over previous specs. Interestingly, I found out the other day as well that if you run your router in "dual band" to support both N and G clients, your wireless speeds on both N and G suffer. So ironically if you have any wireless G clients, unless you really need your N devices to run at "slightly faster than G but nowhere near N speeds", you should still run G only.
Cool beans! I'm liking some of the features I'm seeing on the box these days from some of the WiFi routers. A nice change from the utter crap they used to shlep out where the only smart thing to do was check if you you run a custom firmware on the device and replace the junk software sold with it.