At the moment I fully admit to using someone elses wireless internet. In that, they have left it wide open for everyone to use, no protection or nothing.
I didn't hack a thing - merely enabled my wireless.

Wrong or justified?

You're stealing and you're going to hell!

Leaving it open can be seen as permission for others to use it, though more likely they're a noob who doesn't know how to secure their connection. Personally I have a wireless connection wide open right now (not because I'm a noob :P), I could secure it but that means more hassle, plus the range isn't really good enough for anyone but my next door neighbours to use it, and I could tell if anyone outside my house were using it anyway. If I lived in an apartment building I would probably secure it.

I wouldn't mind someone stealing it for general browsing and such, as long as they're not using p2p or doing anything illegal, plus it gives me plausible deniability if they ever find trace back my IP from any kiddie porn rings :D. I'm not as security paranoid as most other people with my training (I also log into windows as an administrator by default, shock horror!).

So ethically, if you're not doing anything bandwidth intensive or illegal (although stealing wireless is probably by itself illegal, technically), go for it.

Oh yeah, this reminds me (from here):

It's wrong but they have no-one to blame but themselves for not securing their network. It's not like it's hard to do.

IMO if you don't know the hazards and limitations of the technology you use you shouldn't be allowed to complain when it goes wrong or when people take advantage of you.

Its only temporary til we get the net in our flat.
Though I might ask our next door neighbours if I can use theirs in the meantime, cos the signal is stronger and its secure.

There's always this: go to the place that has the unsecured network, and offer to secure it for them, in exchange for use of it till you get the net in your flat.

Of course, you then have to know how to secure a wireless network.

^^ she cant really use it reliably though. The signal is so weak it come and goes so its not worth the effort.