Caffeine
Used by 19 peoplelightheadsw.com ↗

“And not to forget Caffeine - an essential utility when you depend on your Mac not going to sleep while you present.”
Pascal Finette Interview, Entrepreneur, investor · via Uses This 
“Caffeine - stops my MacBook from dimming/locking itself.”
Colin Gourlay Interview, Interactive story developer (ABC News, Australia) · via Uses This 
“Caffeine for easy control over when my laptop can and can't go to sleep.”
Adrian Holovaty Interview, Web developer (EveryBlock, Django), musician · via Uses This