WPSD & YSF - Getting Started with WSPD & YSF
Echolink - A great app to have on your phone or computer in case you don't have a radio.
QRZ - Connect with other Ham's.
Repeater Book - Find repeaters close to you to connect to.
Chirp - a free, open-source tool for programming your amateur radio.
DMR? - Digital Mobile Radio information.
Absolute Tech - Great resource for tech questions
ARRL Frequency Allocation - Must have information.