The 74HC595 is very useful in expanding how many pins a microcontroller can write to. Use 3 to write to 8!
The 24LC16B is a16K Bits x 8 I2C serial EEPROM device.
Handy for extending the "brain space" of any microcontroller!
The 25LC640 SPI Serial EEPROM is a 8-bit x 8192 words SPI EEPROM.