In the middle of the 19:th century Sir Thomas Wade introduced a system of transcribing Chinese characters with Latin/Roman characters. Professor Herbert Allen Giles published a modification of the same system in 1912. The system uses Latin/Roman letters for sounds rather similar to the actual letters - which is not always the case with Pinyin. Aspirations are marked with apostrophes. If marked, the tones are indicated with superscript numbers.
This system was, for many years, the most widely used to romanise Mandarin Chinese. People in the west are also still very familiar with transliterations written with this system (e.g. by rather saying "Peking" and "Mao Tze-Tung", that in Pinyin would be written as "Beijing" and "Mao Zedong"), even if Pinyin often is the recommended system to be used. The sytem is used in Taiwan for transliterating place names, street names and people's names. It also occasionally appear in Western publications (especially older works).
Enter the romanisation for for a syllable in Mandarin Chinese according to Pinyin or Wade-Giles, and this glossary will give you the corresponding transliteration according to other systems!
Further reading:
aspiration,
Bopomofo,
Chinese phonetics,
hanzi,
Pinyin,
tones,
Zhuyin 
