Running a simple syntax check over your files is a good way to save time. This can be when testing code but best practice is to not to even commit code that contains syntax errors.
You can syntax check a single file using the -l (lowercase L) flag with the PHP executable like this.
$ php -l file.php
Unfortunately this can only check one file at a time so I set about trying to find a good way of checking a whole project at once. There are a couple of scripts available on the internet, but I set about creating my own solution using the phplint task in Phing. This means that I can just create a fileset and feed this into the phplint task without having to rewrite the whole thing if I wanted to include (or exclude) a particular directory or file.