The 8-pin AtTiny x5 MCU (ie. AtTiny25, AtTiny45 and AtTiny85) can be set to use it's internal clock source to something as high as 16Mhz without any external components by setting PLLCLK which would enable the internal PLL for high frequency clock generation (no crystal or capacitor or what ever is needed).
This feature can be used to implement a simple and cheap USB device as in V-USB with ATtiny45 / ATtiny85 without a crystal
Is there any AVR (AtMega or AtTiny) with more than 8 pins having this feature (referring to PLL)?