All of the ATtiny microcontrollers that come in PDIP packaging, with links to datasheets and summary sheets, as of 2013-12-31. Clock speeds are for fastest version; I/O and ADC counts, where applicable, are for PDIP package.
ATtiny13/13V Datasheet, Summary 6 I/0, PDIP8P3, 1kB flash, 2 PWM, 4ch 10bit ADC, 20MHz
ATtiny13A Datasheet, Summary 6 I/O, PDIP8P3, 1kb flash, 2 PWM, 4ch 10bit ADC, 20MHz
ATtiny2313/2313V Datasheet, Summary 18 I/O, PDIP20P3, 2kB flash, 4 PWM, 20MHz, USI, USART
ATtiny2313A/4313 Datasheet, Summary 18 I/O, PDIP20P3, 2/4kB flash, 4 PWM, 20MHz, USI, USART
ATtiny24/44/84 Datasheet, Summary 12 I/O, PDIP14P3, 2/4/8kB flash, 4 PWM, 8ch 10bit ADC, 20MHz, USI
ATtiny24A/44A/84A Datasheet, Summary 12 I/O, PDIP14P3, 2/4/8kB flash, 4 PWM, 8ch 10bit ADC, 20MHz, USI
ATtiny25/45/85/25V/45V/85V Datasheet, Summary 6 I/O, PDIP8P3, 2/4/8kB flash, 3 PWM, 4ch 10bit ADC, 20MHz, USI
ATtiny26/26L Datasheet, Summary 16 I/O, PDIP20P3, 2kB flash, 2 PWM, 11ch 10bit ADC, 16MHz, USI
ATtiny261A/461A/861A Datasheet, Summary 16 I/O, PDIP20P3, 2/4/8kB flash, 3 PWM, 11ch 10bit ADC, 20MHz, USI
ATtiny28L/28V Datasheet, Summary 11 I/O + 8 input, PDIP28P3, 2kB flash, 4MHz
ATtiny48/88 Datasheet, Summary 24 I/O, PDIP28P3, 4/8kB flash, 6ch 10bit ADC, 12MHz, SPI, TWI
All of the ATmega microcontrollers that come in PDIP packaging, with links to datasheets and summary sheets, as of 2013-12-31. Clock speeds are for fastest version; I/O and ADC counts, where applicable, are for PDIP package.
ATmega164A/164PA/324A/324PA/644A/644PA/1284/1284P Datasheet, Summary 32 I/O, PDIP40P6, 16/32/64/128kB flash, 6 PWM, 8ch 10bit ADC, 20MHz, 2 USART, SPI, TWI, QTouch
ATmega16/16L Datasheet, Summary 32 I/O, PDIP40P6, 16kB flash, 4 PWM, 8ch 10bit ADC, 16MHz, USART, SPI, TWI
ATmega162/162V Datasheet, Summary 35 I/O, PDIP40P6, 16kB flash, 6 PWM, 16MHz, 2 USART, SPI
ATmega164P/164PV/324P/324PV/644P/644PV Datasheet, Summary 32 I/O, PDIP40P6, 16/32/64kB flash, 6 PWM, 8ch 10bit ADC, 20MHz, 2 USART, SPI, TWI
ATmega48/48V/88/88V/168/168V Datasheet, Summary 23 I/O, PDIP28P3, 4/8/16kB flash, 6 PWM, 6ch 10bit ADC, 20MHz, USART, SPI, TWI, QTouch
ATmega48A/48PA/88A/88PA/168A/168PA/328/328P Datasheet, Summary 23 I/O, PDIP28P3, 4/8/16/32kB flash, 6 PWM, 6ch 10bit ADC, 20MHz, USART, SPI, TWI, QTouch
ATmega48P/48PV/88P/88PV/168P/168PV Datasheet, Summary 32 I/O, PDIP28P3, 4/8/16kB flash, 6 PWM, 6ch 10bit ADC, 20MHz, USART, SPI, TWI, QTouch
ATmega16A Datasheet, Summary 32 I/O, PDIP40P6, 16kB flash, 4 PWM, 8ch 10bit ADC, 16MHz, USART, SPI, TWI
ATmega32/32L Datasheet, Summary 32 I/O, PDIP40P6, 32kB flash, 4 PWM, 8ch 10bit ADC, 16MHz, USART, SPI, TWI
ATmega32A Datasheet, Summary 32 I/O, PDIP40P6, 32kB flash, 4 PWM, 8ch 10bit ADC, 16MHz, USART, SPI, TWI
ATmega644/644V Datasheet, Summary 32 I/O, PDIP40P6, 64kB flash, 6 PWM, 8ch 10bit ADC, 20MHz, USART, SPI, TWI
ATmega8/8L Datasheet, Summary 23 I/O, PDIP28P3, 8kB flash, 3 PWM, 6ch 10bit ADC, 16MHz, USART, SPI, TWI
ATmega8515/8515L Datasheet, Summary 35 I/O, PDIP40P6, 8kB flash, 3 PWM, 16MHz, USART, SPI
ATmega8535/8535L Datasheet, Summary 32 I/O, PDIP40P6, 8kB flash, 4 PWM, 8ch 10bit ADC, 16MHz, USART, SPI, TWI
ATmega8A Datasheet, Summary 23 I/O, PDIP28P3, 8kB flash, 3 PWM, 6ch 10bit ADC, 16MHz, USART, SPI, TWI, QTouch
Atmel application notes that are relevant to AVR development. Big list here
AVR*
AVR035: Efficient C Coding for 8-bit AVR microcontrollers
AVR040: EMC Design Considerations
AVR042: AVR Hardware Design Considerations
AVR053: Calibration of the internal RC oscillator
AVR072: Accessing 16-bit I/O Registers
AVR073: Acessing 10- and 16-bit registers in ATtiny261/461/861
AVR100: Accessing the EEPROM on tinyAVR and megaAVR devices
AVR103: Using the EEPROM Programming Modes on tinyAVR and megaAVR devices
AVR106: C functions for reading and writing to Flash memory on tinyAVR and megaAVR devices
AVR120: Characterization and Calibration of the ADC on an AVR
AVR125: ADC of tinyAVR in Single Ended Mode
AVR126: ADC of megaAVR in Single Ended Mode
AVR128: Using the Analog Comparator on tinyAVR and megaAVR devices
AVR130: Using the timers on tinyAVR and megaAVR devices
AVR131: Using the 8-bit AVR High-speed PWM
AVR133: Long Delay Generation Using the 8-bit AVR Microcontroller
AVR151: Setup and use of the SPI on tinyAVR and megaAVR devices
AVR156: TWI Master Bit Bang Driver A TWI master driver for devices lacking USI and TWI modules
AVR182: Zero Cross Detector on tinyAVR and megaAVR devices
AVR200: Multiply and Divide Routines
AVR201: Using the 8-bit AVR Hardware Multiplier
AVR202: 16-Bit Arithmetics on tinyAVR and megaAVR devices
AVR205: Frequency measurement made easy with Atmel tinyAVR and Atmel megaAVR
AVR222: 8-Point Moving Average Filter on tinyAVR and megaAVR devices
AVR223: Digital Filters on tinyAVR and megaAVR devices
AVR242: Multiplexing LED Drive & a 4x4 Keypad on tinyAVR and megaAVR devices
AVR274: Single-wire Software UART on tinyAVR and megaAVR devices
AVR290: Avoid Clock Stretch with Atmel tinyAVR Demonstrates a TWI slave driver for ATtiny20/40
AVR305: Half Duplex Compact Software UART on tinyAVR and megaAVR devices
AVR306: Using the AVR UART in C on tinyAVR and megaAVR devices
AVR307: Half Duplex UART Using the USI Module on tinyAVR and megaAVR devices
AVR310: Using the USI Module as a I2C Master
AVR311: Using the TWI module as I2C slave on tinyAVR and megaAVR devices
AVR312: Using the USI module as a I2C slave on tinyAVR and megaAVR devices
AVR315: Using the TWI module as I2C master on tinyAVR and megaAVR devices
AVR314: DTMF Generator on tinyAVR and megaAVR devices
AVR316: SMBus Slave Using the TWI Module on tinyAVR and megaAVR devices
AVR317: Using the USART on the ATmega48/88/168 as a SPI master
AVR318: Dallas 1-Wire master on tinyAVR and megaAVR devices
AVR319: Using the USI module for SPI communication on tinyAVR and megaAVR devices
AVR341: Four and five-wire Touch screen Controller using tinyAVR and megaAVR devices
AVR351: Runtime calibration and compensation of RC oscillators
AVR410: RC5 IR Remote Control Receiver on tinyAVR and megaAVR devices
AVR415: RC5 IR Remote Control Transmitter on tinyAVR and megaAVR devices
AVR446: Linear speed control of stepper motor on tinyAVR and megaAVR devices
AVR911: AVR Open-source Programmer for tinyAVR and megaAVR devices
AVR1016: AVR Training QTouch Xplained
AVR1200: Using External Interrupts for megaAVR Devices
AVR1201: Using External Interrupts for tinyAVR Devices
AVR1908: QTouch Xplained Hardware User Guide
AVR4027: Tips and Tricks to Optimize Your C Code for 8-bit AVR Microcontrollers
AT*
AT01486: Low Cost Capacitive Touch TV Control Keypad
AT1886: Mixing Assembly and C with AVRGCC
AT03152: Proximity Sensing for SAR
AT03816: QMatrix Control Panel for In-Home Display 7-key touch solution w/ SPI slave interface on ATtiny4313
QTAN*
QTAN0015: Power Supply Considerations
QTAN0017: Checking the Effects of Noise
QTAN0031B: Avoiding False Touch Inputs
QTAN0079: Buttons, Sliders and Wheels Touch Sensor Design Guide