in nearly all browsers* you can overwrite the window location in the
"onunload" event.
that means you can "keep" the user on a site. when you type a new url
in the address-bar, javascript overwrites it. thats a paradies for
fishers, porn-site-hoster etc......
here the html/javascript code:
Link 1
Link 2
Link 3
Link 4
cheers
Tobias Boonstoppel
ps: * i testet it on firefox (linux / window) opera (linux) and
internet explorer.