Don't park your car on the street if you can help it, unless you have a locking gas cap! That's one way to save gasoline. No, I didn't learn the hard way, but with prices the way they are, gas thievery is a potential problem no matter where you live, city or country.
A locking gas cap is money well spent, but even then, if you can possibly park in a garage or enclosed area, don't leave your car on the street. You may never know how much gas you saved that way.
On Lehman's blog: About those gas prices...
What did I miss? Let me know here or there, so we can all benefit from it. With gas prices the way they are, we need to use every trick there is to lengthen the time between fill ups.