10 Commandments might apply to more than just Facebook!
Check out these 10 Commandments for Facebook Applications. They are pretty good commandments for software in general. I especially like:
"Make it simple. Users DO NOT read.", from FaceReviews
Yup, I have seen that time and time again with BlogBridge. Hard to believe. But true. Of course there's the 1 in a thousand who ask for more documentation, but they are very rare.
[if you are interested in Facebook, take a look at BlogBridge's Guide of Facebook blogs and feeds]