Because I hate the IPv6 servers, I searched for an IPv4 one.
I found one with this :
*Duration : 15 (or 7 days, I don't remember)
*Retention : 191 days
*Max speed while free access : 250 kb/s
How does it work ?
Register with a spam mail, and go reserve an ad access.
When you register yourself on the ad they ask you to register and than you say you do it, you are credited of X Gb (said).
It's in french, but you can use the Google translator.