Thilak has posted a good article on his site telling users how to search for a free Rapidshare account .

Rapidshare periodically releases free account for its users which are valid for 2 days . After 2 days they are not deleted but the account can be extended by user free of cost by collecting Premium Points . Points can be collected by Uploading materials and making other users download them .

I tried the latest technique mentioned in the site and it worked for me and i got a free rapidshare account for 2 days . Give it a try might work for you .

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