Usually when building a dynamic website (such as a social networking site), you want to makes as many things as possible be automatically generated with as few inputs from the user.
Usually.
While the above remains true, there are some things that you may want to be optionally manual. Especially for the pieces of information that enable the essential functionality of your site.
Say that you run a mobile site. You can automatically detect what kind of phone they have. When you do, you enter it into the database. The functionality of your service to them banks on knowing what kind of phone they have. What if you detected it wrong? What if you couldn’t detect it? You should have a back-up option, such as: Not your phone model? Select here (link).
I actually thought about this because I was using the restroom at the mall the other day, and it was those automatic toilets that I hate. One too many times have I had one not flush when I was finished. I don’t like leaving my remains in there! How embarrassing! But these restrooms were different. There was a little manual flush button at the top, should the sensors not detect your presence (or lack thereof).
This was a perfect parallel - flushing is the #1 functionality of the toilet when you are done with it. If it is automatic, there should be the manual backup to flush if something goes wrong with the mechanics.
Think about it next time you use automatic toilets.

April 3rd, 2008 at 4:43 pm
Yes, I do dislike that about automatic toilets! But…have you ever had one flush while you were using it? I have…and it certainly in not pleasant (as many automatic toilets splash when they flush). Anyways, good point about having another option available for when things don”t go as planned.
April 3rd, 2008 at 4:44 pm
Yes, having one flush while you are on top is not exactly pleasant, either.