I just came across a site, leapfish.com, where it attempts to value your site/blog based on certain factors like the number of search results from Yahoo and Google and how long the domain name is (I got points taken off for having a longer name).
It creates two values: an estimated base value and an estimated actual value. The base value is the minimum the site is worth and the actual value is based on the factors combined with recent web site sales. My actual value turned out to be $9,842 so if you want to write that check, click the email button and I'll let you know who to make it out to!
This reminds me of another finance site from about one year ago. I forgot the name of the site, but it was a rather popular finance site. Apparently someone offered the two writers $2000 for their blog and they sold it. The buyer promised to continue the blog and offer many new things (new writers, etc.). A few weeks go by and nothing updates. Then a little over a month goes by and people start to realize that the site is dead. Some guy paid $2000 for the site and did nothing with it! Talk about a waste of money.