A list of the 5 libraries in the architecture atmelavr.

avdweb_VirtualDelay Allows using (multiple) delays without blocking code execution. Arduino Uno and Zero.
DHTStable Stable version of library for DHT Temperature & Humidity Sensor
fp64lib Handcrafted 64-bit floating point routines for AVR/arduino microprocessors.
Mcp3208 Arduino library for the MCP320x 12 bit ADC family.
PJON PJON is an open-source, multi-master, multi-media bus network protocol