I will never be afraid to give out my email address again. Well, maybe not my actual address, but I will give away my sneakemail address. This service (http://sneakemail.com), will allow you to generate a random looking email address like "firstname.lastname@example.org" that you can safely give out. It is a disposable address that you can use to sign up for a given site, tag it for that purpose and then if you get any spam from that site, delete the address.
However, I have recently taken this one step further. I have created a spamtrap address that will automatically report spam to spamcop and blacklist the IP address of the hosting servers. So, instead of deleting the address, I simply re route it to the spam trap and increase the power of the blacklist.
1. Sneakemail (free accounts available)
2. Spamcop reporting account
3. Automatic report account - the trap account (Thunderbird Reporter or Lotus Notes reporter )
Then you can use your disposable email addresses as you need and have them divert to the spam trap if they start to get spammed.