TLA’s Text Link Price Calculator requires you to enter your website address, website category, # of text links to be sold, and to choose between site-wide or single-page links. To the right of this form is a “map” of a standard website layout. You choose where you plan on placing the text links and the price is weighted accordingly.
The results aren’t that accurate – as in, the tool doesn’t consider many other factors that might affect the price you might charge your advertisers. There is definitely room for improvement. Right now it seems their algorithm for finding an estimated price is based on link popularity, link position on page, single or site-wide, quantity of links being sold, and possibly some other calculations made behind the scenes. For noobs or semi-experienced people, this tool might give a good example of the “going rates” for text link these days.
You might also be interested in Patrick Gavin’s Link Building Blog.