Stimator is a web service that gives the value of a website by taking different parameters into account. Touted as a “real website value estimator” it checks the web for backlinks, popularity in social media sites and gives an estimate in USD.
Stimator may not give the best results for estimating the real value of a website but it gives a rough value of a website. Stimator is a fun way to see how much your blog is worth. Enter the URL of any site and click enter, it analyzes various parameters ranging from TLD to popularity, backlinks etc. You can read about the factors that weighed in for calculating the value for a website.
If you are serious in selling your website then this may not be the right tool to get the value, but atleast it gives a rough value of the site.