Rate Limiter Script (PHP/Nginx/Ubuntu) -- 2

I am in need of a simple php+Memcahe script or an Nginx rate limiter setup to help me prevent a user with the same IP from opening pages on my site too quickly. My initial thought was to use Nginx to accomplish this, but other people were mentioning that using php+memcache would be easier. I need someone who understands this and can best implement it for me immediately. Must be done tonight. Please begin job quote with "RAIN" and explain in quote how you would best accomplish this, otherwise you bid will be rejected. Thanks!