Some keywords are searched very often on http://inventory.overture.com/d/searchinventory/suggestion/ For example this Web Directory is searched over 500 times a day Searches done in January 2007 Count Search Term 15350 web directory Post here some Figures from Popular Keywords :- Could turn up some interesting results
Those 3 make up the directory industry for the most part and because it is so, those keywords are damn hard to win over. I will do some research, but I had found some others too. Estimated info, but for web directory you need 20-40 links with web directory in the anchor text. Some long tail variations in there. This is my favorite keyword tracking site http://freekeywords.wordtracker.com/
Here are a few common ones submit url - 544 free url submit - 104 add link - 79 add a link - 42 add url - 860 add url free - 181 business directory - 978 business directories - 81 paid directory - 14 paid directories - 12 web directory - 336 web directories - 109 web site directory - 283 free web directory - 75 free directory - `102 free directories - 17 free reverse cell phone directory - 1019 free reverse phone directory - 798 You can verify with the tool I listed in the above post.
The thing to remember though when checking keywords is that the numbers are often inflated in the keyword checkers from the same types of site owners doing their research.
I guess the keyphrase is very popular as well. The phrase is pretty logic and there are plent of results out there: http://www.google.com/search?hl=en&q=I+hate+dmoz&btnG=Search