Great site to register work/copy/articles etc with - offers a plagiarism service that's included in the price too! I use it regularly especially when working for new clients on the other side of the world. You get an image of your copy that you download which has a date and registration number on it - you send the image to clients and release the copyright when you get paid - very good idea especially on freelance writing sites that do not vet project owners that well. I highly recommend SampleSafe to all serious writers and authors - the registration number adds that bit of protection to work and it also looks very professional. You can sell articles through the site too! There's a free trial period for new users which is handy.

I found this site which is a review site as well as a copyright registration website for authors/writers and freelancers. First time users get a free trial period - after this there is a small fee to pay which includes a plagiarism check as well as a copyright registration number for any work/copy/articles/content etc users register with the site before sending the work to clients. Nice idea and very useful way to register copyright and check for plagiarism! Pretty easy to navigate and authors/writers can sell work through the site. Users can also review bad payers and let other freelancers know about any issues they have experienced writing for Internet clients. Highly recommended!