Rating site in PHP

I'm planning on doing a rating site for hotels in a certain region. Before I reinvent t开发者_StackOverflow社区he wheel, are there any complete open source rating alternatives that I just can install on my server?

I know I'm not being very specific, but some functionality that might be good is...

• Add details of a hotel
• Rate and comment a hotel
• Forum is good
• Use google maps to place hotels on a map (I'll perhaps have to fix that one myself)

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You could implement the site, with the admin (adding hotels, including them on a map), and then under each hotel, include a Disqus or Intense Debate code snippet. I managed to evade a serious couple of hours of work this way (using Disqus).

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Have you looked at Pligg? It doesn't have everything you mentioned but maybe you could modify it to your needs.