I have no broken links that I know of but still have like 3k hits to my 404 page from curious surfers each day. Mine is simple and has no popups... here it is
http://yourhigh.com/404.html
on my free host though it is a little more obscure even, it just 404s back to the 'main' page at
http://goodgallerys.com
I get a good number of sales from my 404 pages... I dont believe in popups or traps... I think people get too guarded when they are 'attacked' by malicious popups and it makes them less likely to spend money.