I have heard too many times that everyone should secure their wireless devices, even though I've heard too that neither WEP or WPA, are all that good. However I've seen a lot of unsecured wireless points available in public places and otherwise - so what is the real risk with having my home wireless unsecured?

Without the security, you will have people piggy-backing onto your connection which isn't that bad in itself but it also gives the people with the know-how access directly into your computer. It may never happen but if a hacker wants to get in and plant a trojan, keylogger or other little nasty, not being secure makes it terribly easy for them. A lot of people think there isn't anything they worry about in their computers but then the hackers can do things from your computer and it looks like YOU are the one doing it.

Do you really want to pay for your neighbor or some random teens driving around borrowing your net connection and doing bad things? Thats the reason we have a key for ours now since so many locals are having this issue.

If your device is on and you're driving around.. everytime you come within range of a hub.. your device will attempt to connect. Which is the first place to start.. make sure that your device is set never to automatically connect. THe risks of having someone on your device should be obvious though, any personally sensitive info can be had. People have been caught "trolling" wireless cafes looking for ways into others computers.
I once caught my roommates kids using the neighbors connection in the backyard. Once into the network they could get whatever they wanted off your PC.

Well I know that a couple of meighbours are piggybacking on my wireless - they have even asked me to turn it on several times - and I don't really mind as it's not costing me anymore. I don't like the neither though that my connection could be used by others to nasty stuff and worse yet, making it look like ME.