Chemistry.com is a free weekend starting on October 14th and running until October 16th 2011. This event will start at 12:01AM on the 14th and will end at 11:59PM on the 16th (so basically the entirety of all three days are free).
Chemistry is one of the few major online dating services that has semi-frequent free events so if you’d like to try out a dating service without having to subscribe, this will be one of those opportunities to try. This is actually the first time since June with Chemistry. To see a full list of the previous Chemistry free weekends, checkout this article.