Amy Van Deusen wrote a great post on About.com Gymnastics: Cool Trick: The Layout Full on Beam.
She linked to this fantastic example performed by Kui Yuanyuan (Simplified Chinese:奎媛媛) in the 1997 Worlds Beam Event Finals. Click PLAY or watch it on YouTube:
Circus performers have done double twist and far, far more on “beam-like apparatus”.
Who and how soon will we see an Artistic gymnast compete double twist? Or will the beam need to be sprung more first?
PS
I had forgotten about the Kui Yuanyuan controversy:
Kui went on to win two bronze medals at the 1997 Worlds with her team and on the balance beam.
The balance beam results turned into one of the most disputed events in gymnastics history. Kui performed one of the most difficult routines of all time, yet finished .012 behind Romania’s Gina Gogean, who competed one of the easiest sets performed in World competition during the 1990s. Kui’s rare full-twisting back layout on the beam drew gasps, as did her three split leaps to back handspring, 2 layout step-outs. Kui lost the silver medal as well, when a tie-breaker was put into effect. The results prompted the president of the Federation of International Gymnastics to publicly chastise the judges and tell them they were wrong. …
Gymnastics Coaching.com 