I run a popular Usenet Indexing website which is based on Newznab (http://www.newznab.com). It runs on the paid Plus version but the free version has all the same features except for some regexes which are not important for this project. The frontend is build up around the Smarty Templating system.
What I want is for users to be able to give a UP vote if they think the release is good and a DOWN vote is it's bad. The votes should be displayed in the listings, detail view and should be returned on API calls. Users can only vote once per release but should always be able to change their vote to UP or DOWN but not vote UP a few times for example.
This should be fairly easy to do for an experienced PHP/Smarty coder. There is already an API which is heavily used by our users to automatically download Movies and TV Shows, the fields: upvotes and downvotes just have to be added to the results so external software can act on those values.
Also I update Newznab on a regular basis using SVN and GIT which overwrites any changes. So it should be easy to reimplement after an update or the programming should reside in external files which just have to be re-included after an update.
I can provide a testing environment identical to our current production environment if needed. If I'm happy with the result and delivery time more jobs for the same website may follow in the future.
If you need more information please do not hesitate to contact me.