I share my wi-fi with friends who visit.
I give them the pass phrase - which gets changed regularly.
I never run unsecured wi-fi.

Please read the AP Guide to safer computing...
http://www.ausphotography.net.au/for...369#post197369

The airport (Qantas club) has free wi-fi anyway.

Some of our neighbours had unsecured wi-fi - I left a note in their letter box that I could 'steal' their bandwidth (and in one case could delete their files). They fixed it.

There are people who 'war-drive' - they travel with wi-fi enabled vehicles (usually a notebook with a hi-gain antenna) and steal bandwidth (usually for (c) infringed downloads).
http://en.wikipedia.org/wiki/Wardriving
SO KEEP YOUR NETWORK SECURED!!!

I use NetStumbler for scanning the local area to see who else is out there.