Some good online hangman games for ESL students include "Hangman for ESL Students" and "Hangman" with high-frequency words. Found at ManyThings.org, these Hangman games offer basic graphics and quick gameplay.
"Hangman for ESL Students" offers the player several categories from which to choose, including fruit, farm animals and meat, time, vegetables and parts of the body. This game helps an ESL student reinforce basic vocabulary. The "Hangman" game includes word lists for high frequency and common words. It offers separate games for the 900 most commonly used words in the English language. It also offers games for children in kindergarten through 3rd grade.