I have some sites targeted in a niche that has worldwide customers but my sites are .co.uk. When i go to check the Serps i have a much higher rank if i choose UK rather than .com to see results. Is this solely because my domain ends in .co.uk rather than .com? Also when people in the UK or anywhere else go to Google and do a search isnt it always worldwide results that come up (unless you click the button on the side of Google which states "pages from the UK" (which im sure most people will not bother with). This seems unfair if my target niche is worldwide. I try and go for .com from now on if my niche is targeted worldwide, lesson learned i guess.