A good list, to which I'd add USE YOUR SOFTWARE. I realize this may sound a bit ridiculous, but I can't tell you how often I fire up an app for the first time and within seconds think, "Has anyone ever actually used this damn thing?!" It's beyond frustrating when the tiniest deviation from how, for example, my dad or girlfriend might use an app, causes it to crash.
If within the first few minutes I've come up with 20 different ways to make tasks x/y/z faster, more efficient, less annoying, etc., then you probably haven't used your software enough.
Invariably, bugs, missing features, etc. are a part of every release, but that's no excuse for the big errors, the ones that make your app impossible to use.
Don't give your RSS reader, Twitter client, etc. to your buddies to test. Give it to me. Tell me to kick the crap out of it. Tell me to break it. It needs to be broken, and this can be done only with real-world use.