I would like to have TripAdvisor reviews of a client's restaurant shown on the site, what's the best way to do that? If possible he would like the possibility to check the review first before it is posted to the site.
The best way to do this would be to request access to the Trip Advisor API, available on request here: http://www.tripadvisor.com/APIAccessSupport
They only allow a certain amount per year and under fairly strict rules, but I've put in a request with them last year for something fairly similar as what you are requesting and got it approved fairly fast.
Their API is fairly straightforward (WSDL), but for any follow up questions it's probably best to open a new question. Good luck.