Ubicom / Parallax PIC SX28A Microcontroller

75Mhz max clock & 75 MIPS (1 instruction per clock)
28 pin DIP package, ideal for prototyping.
20 TTL/CMOS/Schmitt I/O pins
136 bytes of SRAM.
2K EEPROM program memory.
Fast IRQ handling.
Functionally very similar to the PIC16C54
Instruction set much like the PIC range (though Ubicom use different mnemonics)
Can use an internal RC oscillator, crystal/ceramic resonator or ext. clock drive.
DIY programmer circuit available. ("Fluffy 2" - see link below)
DIY programmer supported by ICprog (set hardware to "Fluffy programmer")
Free assembler (SASM) and simulator (SXsim) available from Parallax.com
Good support forum

Click here for more info