By asymetrical subscribe/unsubscribe I mean a web service that has one way for subscribing and another for unsubscribing. Typically subscribing is easy - you input your credit card details on a web form and you’re done. If you can subscribe via a web page you should be able to unsubscribe via another web page. But a few online services make it very hard to unsubscribe - I think for obvious reasons. This only serves to annoy users even more - hence making it unlikely a user will ever re-subscribe. 

Now, if you have a field in a form that only accepts certain values don’t you think that it would be a good idea to tell the users of the form what those values are before they’ve filled them in? I am sick of the “invalid email” error after a form has been submitted. Why is so hard to indicate what valid values are beside the field? Or why can’t this be validated in JavaScript? It’s simply a lack of thought by the page designer/programmer.