AVR's ATTiny Series are packaged in a space saving 8-pin case and can easily be programmed via their serial interface. Here are some programs to cover some small tasks , all built with AVR Studio 4:
PLLControl (Assembler)
program the wireless block of an older home phone from Panasonic with an ATTiny 13. Channel switching through pushbutton.
This is the receiver code, as i planned using the RF blocks for a wireless bass guitar system. The transmitter is similar.
the project was never finished as a bluetooth connection is more desirable now.
Program
more about the M54958 PLL chip

RandomLights (Assembler)
This project is now a lot more than only a random light generator. It uses the built in A/D converter of the ATTiny 25/45/85 to control 18 lights forming a circle.
the output clock and data lines are connected to a series of 3 CD4015 shift registers as LED output drivers.
Advance through the modes including power off/sleep with a single button. I used a notebook speaker mounted in the case which is sensitive enough to react on tapping the case. The input network pulls the internal opamp away from the ground rail.
Program
Wiring the A/D converter on ATTiny 25/45/85

SolderingStation (Assembler)
When the controller of my soldering iron broke i had to do something. As the ATTiny 25/45/85 contain an analogue amplifier and A/D converter capable of amplifying the weak signal from a thermocoupled element i decided to use it for controlling my iron. This project uses the A/D converter in 10-bit mode with differential input to regulate the iron to one of 5 preset temperatures.
User input is interupt driven with pushbuttons to increment or decrement through the settings. Feedback is done by flashing the heater LED.
A blue LED serves as power lamp and voltage stabilizer. Any 2.7 - 5 Volt zener would do here but i have masses of those LEDs . The input network is for pulling the internal opamp out of rail-to-rail operation which is doesn't do good. Automatic zerocross-switching the heater is accomplished by using a MOC3042 optocoupled triac in the AC circuit.
Program
Schematic Diagram

USB Interface for Tektronix 4957 tablet using V-USB ( C )
The availability of the V-USB library made it possible to create an USB adapter for connecting this old quality digitizer tablet to modern machines. The device appears as a HID-mouse device with absolute coordinates. The software mostly consist of the V-USB routines and an interrupt-driven serial receiver routine. The ATTiny acts as a code converter and also initializes the tablet. Source code is well commented. The ATTiny is operated from an external 16 Mhz oscillator and should be fused to no CLKDIV, ExtClk (on PB3). No drivers required. Built with AVRStudio 4 and WinAVR (gcc).
Project ZIP
Schematic Diagram

Email me for Questions and suggestions.