The last couple days I've come around to use the keyword suggestion tool it seems to load very fast and return no results for wordtracker or overture, regardless of keyword phrase. Is the tool no longer supported/available? I hope not because I love that tool.
Check out these then.. http://freekeywords.wordtracker.com/ http://www.keyworddiscovery.com/search.html http://www.pagerank.net/keyword-suggestion/ http://tools.seobook.com/keyword-tools/seobook/