A lot of times I just use a z-loc as a cafe lock. I know that is a totally inappropriate use of them but again I live in a very small community with relatively low risks of bike theft.
One thing that you can't overestimate is that it is very important that your bike isn't too pretty and too clean. Most bike thieves in urban areas fence their bike within a few hours, and a dirty or slightly uglified bike might sell for $100 less than a shiny clean new-looking bike. Yes, you can take uglification to extremes (see below) but letting your bike accumulate a few scratches and scrapes and a dignified amount of grime will make it much less appealing to bike thieves.