In SEO it is extremely helpful to know how many sites you are actually competing against for a particular keyword, for this us helps determine how diffiicult it will be to rank well in the major search engiens for that keyword. Currently, the best way of determining the number of sites that you actually compete against is to run an intitle/inanchor search on Google. This search tells you how many sites include a keyword both in the Title Tag of their webpage and the anchor text of a link which points to that page.
Placing ones keywords in the title tag and anchor text are two of the most important strategies in SEO. Knowing how many sites do this for a particular keyword indicates how many sites are being optimized for that keyword, thus indicating the number of sites you are competing against.
To perform a intitle/inanchor search for an individual keyword go to Google and type in: intitle:”keyword-phrase” inanchor:”keyword-phrase”. To perform this search for a large number of keywords use Keyword Elite (currently, Keyword Elite is the only program which offers this option, to the best of my knowledge).