I have searched in Google.co.uk to see who comes up first for single letter (alphabets).

Here are the results…

• A is for Argos.co.uk
• B is for Bbc.co.uk
• C is for Currys.co.uk
• D is for Debenhams.com
• E is for Ebay.co.uk
• F is for Facebook.com
• G is for Maps.google.co.uk
• H is for Live.com
• I is for Itv.com
• J is for JohnLewis.com
• K is for Klm.com
• L is for National-lottery.co.uk
• M is for uk.msn.com
• N is for Next.co.uk
• O is for o2.co.uk
• P is for Paypal.co.uk
• Q is for Qvcuk.com
• R is for Rightmove.co.uk
• S is for Sky.com
• T is for Tesco.com
• U is for Youtube.com
• V is for www.virgin-atlantic.com
• W is for news.bbc.co.uk/weather
• X is for Xbox.com
• Y is for Youtube.com
• Z is for Zara.com

The interesting part is the letter “u” showing youtube.com in Top spot and sub-domains & sub-folders are given equal importance as long as they are relevant and satisfy the Google search algo.