All About Birds is a great resource from the Cornell Lab of Ornithology that includes an online field guide (with pictures and sounds) and great advice for getting started birding.

eBird is a great way to keep track of the birds you have seen and contribute to a world-wide database of bird sightings at the same time.

WhatBird.com is an online field guide with an innovative identification system, allowing you to try to identify a bird by choosing characteristics like color, size, shape... even area and time of year. They also have a new iPhone application which I love.

The Travis Audubon Society is our local chapter of the national Audubon Society.  They have great classes and field trips in the Austin area for birders of all skill levels.

Hornsby Bend is the best place to find birds in the Austin area, and probably in central Texas.