Dalvik DEX

Good binary formats rock. Reading the ELF spec was quite eye-opening for me.

Dalvik's DEX format is another nice one.

Interestingly, Dalvik is the brainchild of Dan Bornstein, who was at Kaleida Labs (RIP), where he worked on ScriptX, one of the many avant-garde codes that fell victim to the WWW-induced ice age of GUI innovation.