I've got one client who runs a newsletter, and uses a double opt-in system to build their list. We've been considering offering a "second chance" sign-up for people who do the first sign-up but never complete the confirmation step.
Has anyone ever tried this? Is it worth the trouble, or would it just be an irritation to the receiver?
And, if we do set this up, how long an interval do people think makes sense to wait before offering a second chance sign up?
One of the online job sites does something similar to this which might be adapted to your app. Basically, if a visitor loads the sign-up form and then clicks the back button (and perhaps any other link other than "Submit") then a pop-up asks if they'll reconsider. There's a link to launch it on one of my sites, see your stickymail.