Is there a short word or slang for "matchmaker"?

Cupid might be a good idea.

Play Cupid: to try to arrange for two people to fall in love.

He was playing cupid when he introduced John to Sheila.

According to ldoce:

a character based on the Roman god of sexual love, who was the son of Venus. Cupid is usually shown in pictures as a young boy with wings, holding a bow and arrow . His picture is often used on Valentine card s to represent love. People sometimes say that they have been hit by Cupid's arrow when they have started to have romantic feelings for someone.

Accroding to MSN Dictionary:

Synonyms for matchmaker: marriage broker, go-between, fixer, intermediary, cupid

Here is are some words:

proxy
cupid