The AVR family of microcontrollers is only available from Atmel (unlike the 8051) but Atmel by themselves provide a wide range of parts, from the Tiny to the Mega. Different packages, pin counts, flash, ADC, ... you can probably find one to do what you want. They are RISC processors, and while they run at slower speeds than we're used to in 8051s, their performance is excellent. Most if not all support in circuit programming, and a development board from Atmel provides the PC interface for programming; the developement software (IDE, assembler and simulator) is free. Furthermore, the C compilers are mostly very inexpensive (less than 200 USD for my CVAVR compiler).

Check out www.AVRFreaks.net, the AVR forum.

Dennis