I still prefer spamex.com
This story was on digg:
Find_out_who_gives_away_your_email_address_with_Gmail_trick
Links to hedir.com/introduction/about17942.html and the mirror is here.
But I use spamex.com and it does the same thing and works much better. The spammers can’t just drop the “+whatever” to get to your real addy. I can host a domain name there for my own email use. It’s great.
Edited to add: spamex.com is free. I have a premium account but that’s not required. For each case of giving out an email addy you create a forwarding alias. Then if u get spam at that addy, you not only know where it came from but you turn that alias off to stop the spam “I GET NO SPAM” and this is how. 
I host a domain there so I have my own domain name email. It’s fantastic.