First ... nothing open ... because if you do so, anyone around your location within half a mile could mess with you easily .. let alone anyone malicious, or anyone just wanting free access.
But yes.. you *can* run multiple wireless networks. I use my Cisco Linksys 2100L for my gateway .. it also allows laptops. I have a bridged wireless network from one side of the house, to the other, on Buffalo N based routers ... the other side of the house I have my 722k dish box, my Bluray, my Wii (turned off wireless), my Onkyo AV reciver (absolutely freakin' awesome hearing RadioParadise.com through 7.1) and one of my older PC's all hooked at the far side through the second wireless network.
Now when I'm in my back office, watching the Sling Adapter on my receiver ... 8 megs of traffic doesn't have a hit on my primary router, just the secondary network, and it doesn't cause problems on the wireless network because that secondary is N based and my main is still G.