>The problem is if you turn it off years before because you don't use that technology, then start using it, you forget it's there. I had no idea there was a JavaScript forum for that reason.

We have the default opt in and it would not be a good idea to opt in again later on. I think once an option is turned off, it is the responsibility of the member to verify his settings from time to time to decide if he or she wishes to enable it back later. This is how Facebook and many other sites are using as far as the approach goes. Everything I turned off in Facebook, for example, as far as blocking applications and so on, are off and showing in my profile that I can decide to turn them back on at any time. That site is quite exceptional BTW in the way it changes its settings on a weekly basis. This is not a good example to follow as they force the users to keep a look at their profile almost every week. But, it is just an example on the topic. I could have picked Twitter for example. :)