The cool kids know that inbound links are valuable context for users of a web app. The best apps go out of their way to hang on to that context even if they need to interrupt you for something else. A very nice case from Flickr: I saw a Flickr link on some page and clicked it. However before I could continue, I had to do the flickr/Yahoo merge. However to do the merge, I had to setup a Yahoo account. However to do that, I had to click an activation link in an email. When I clicked the link, I was sent back to Flickr for the merge, went through a slight merge flow and was dropped back at the original picture. That's a
(some webpage) => flickr merge => yahoo setup => yahoo Find an ID that isn't used flow => yahoo setup => yahoo activaton email => flickr merge process => flickr merge OK => the link I clicked - without missing a beat. Very nice. Not that I had to do it - but that I wasn't punished for going through the boring forms.

If only Windows was like that. If only modal dialogs were like that. If only Microsoft update notifications and security alerts were like that.

(note. I don't particularly like that fact that they couldn't just have come up with a "stupid but workable" default translation so the whole process would have been needless. But at least they didn't try to sell me something in the process)