I was a bit slow to find this one - so here's a quick tip. If you want to easily scroll through web pages or documents, just drag on the track pad with two fingers (if you have a Macbook). Simple and very effective. And it's smart enough to be reliable - no gesture-related false positives.
Oh, and you can also scroll sideways. Awesome.
[Update, thanks for the comment Anonymous. You can turn this on and off in the System Preferences. Just choose "Keyboard and Mouse", Trackpad tab and check "Use two fingers to scroll".]