do you know any free (if possible) services which monitor domain and when become available (expired) is notiffy you via email?

Like someone have a domain and you have high interest to immediatelly take over it when he let it expire.

I found these services to periodically check domains if expired:

http://www.domaintools.com/monitor/domain-monitor/# (free, up to 100 domains)
http://www.domainnameshop.com/domainwatch.cgi (very simple, no signup)
(currently unavailable)