I hate to keep harping on this, but there’s an STM32 in a 64-LQFP with 132K RAM and 512K flash (that’s a lot more RAM than we have in the USBizi) (runs at 120 MHz) for $11.44 in ones. Little package, big power.
Actually, the STM32F405RG in 64-LQFP runs at 168MHz… :). That is also what i’m interested in. 2cm x2cm board with lipo psu/fuel gauge/charger. nice small portable solution…