LoadImpact is a new website that allows you to load test your website. They provide free testing with 50 simulated clients hitting your website. Anything larger than that and you will need to pay for it.
Here is a load test that I ran on my web-site: www.aggregatedIntelligence.com
View the actual results at: https://loadimpact.com/result/www.aggregatedIntelligence.com-ba9c45ccf7201699e699ab55276b43e1