Extract HTTP URLs from text (html for instance)

$ curl -s http://www.iopixel.com | grep http 
     | perl -pe "s|.*(https?://.+?)[^/?=.$&+,:;@-a-zA-Z0-9].*|1|g" | sort | uniq        
http://bit.ly/tip-off-ios-store
https://twitter.com/iopixel
...