Webmasterkey is a wordpress plugin to add google, yahoo, bing, alexa site verification meta tag from admin. I think it will be handy for webmaster.
Quick links for Google,Yahoo and Bing,Alexa webmaster tool
how to collect meta tags
I know max ppl are smart enough and can do it easily but some ppl are not mcuh technical and don no how to upload file or add meta tag in theme file and where. so, to get google meta tag key go to Google Webmaster, login using your google id and your site. See image bellow and check you will see something like this. Copy meta value (red underline in screenshot)