I have been very amazed by the STM32 microcontrollers from ST Microelectronics, which feature a 32 bit ARM core and all kinds of peripherals (12 bit A/D converters capable of a few MSPS, 12 bit D/A converters, 32 bit timers, I2C, SPI, CAN, UART, USB, Ethernet MAC, etc.).
It’s very interesting that you can have a high performance ARM microcontroller for the price of an 8-bit microcontroller. The low-end ones have prices starting from about 1.2$, and the high-end ones usually cost less than 10$.
Another interesting thing is the high-speed DAC integrated in some devices from the STM32 family. This family includes a wide range of microcontrollers, from the entry-level ones based on ARM Cortex M0, to the midrange ones based on Cortex M3 and the high performance ones based on Cortex M4, which feature a DSP and a FPU. The high-end models can run a speeds up to 168 MHz (having a performance of 210 DMIPS).
ST also has a low-cost programmer/debugger called ST-Link, which costs about 30$.
If you want to play a little with the STM32 microcontrollers, please check this STM32 development board.