I have been seeing this term going around for a little bit now but never really digged into it.
What is PinYin names/domains exactly?
Why is getting so popular?
What are examples of these names?
Pinyin, or Hanyu Pinyin, is the official phonetic system for transcribing the Mandarin pronunciations of Chinese characters into the Latin alphabet in China, Taiwan, and Singapore. It is often used to teach Standard Chinese and a pinyin without diacritic markers is often used in foreign publications to spell Chinese names familiar to non-Chinese and may be used as an input method to enter Chinese characters into computers.
Source Wikipedia
Why it's popular - because it's used by people in China for typing into computers.