free long distance

asides from providing free information 1-800-FREE-411 offers 5 minutes of free calls anywhere internationally just say "free call" from the main menu.
The caller ID will display 1-800-373-3411 (800free411) and not your actual number. [EDIT - Free 411 has been passing the callers CID info recently, and several people have stated that international calls no longer work thru this service] No longer provides "free call" option. 

1-800-980-PHAD provides 10 minutes of free US/CAN calls. Your number will be displayed on the caller ID screen. Does not work from payphones last time I checked. [EDIT - PHAD no longer works]

http://ringplus.net provides free international calls via a local access number, you do have to sign up for an account and pin number from there website. Your caller ID shows up. - not useful for payphones since all access numbers are local numbers. - Unable to access website - likely no longer available. 

If you have a google voice number, you can pretty much have free home phone service by combining it with a gizmo account. Google voice numbers can call gizmo numbers for free, and gizmo accounts can call toll free numbers for no charge, so using one of the above toll free methods will get you free outgoing calls. by using the ATA that  http://obihai.com is selling

EDIT -
you can also make calls to the US with the with http://callingamerica.com  [EDIT - no longer provides FREE calls]

EDIT- 1-29-10
http://phonehog.com provides free calling card service, i have never tried this service so I do not know how it is, just providing information.

http://www.freebuzzer.com/en/index.php?  another service I just located... you enter your number, and the destination number in the website, and the call is connected.