MCU 8051 IDE is a fully featured integrated development enviroment for MCS-51 based microcontrollers. It consists of a compiler, an advanced text editor (with highlighting, validation, and completion), a simulator, a scientific calculator, a hex editor, and many other things. Currently, this program supports only assembly language and a few microcontrollers.
avrLab tries to be an complete IDE for the AVR microcontroller chips from Atmel. It offers an editor with syntax highlighting which has standard editor commands like copy, cut, paste, goto line, search, and replace. Additionally, it includes support for tavrasm (a compiler for the AVR assembly language), uisp (used for the communication to the AVR), and much more.