Below are links to some websites which observers find useful.
A Catalog and Atlas of Cataclysmic Variables
International Supernovae Network
Variable Stars Observer - software to help you to plan and log variable stars observations
Obsvar - planning tool which uses AAVSO or AFOEV prediction data and other criteria you specify
Guide 9 - a full-featured star charting and desktop planetarium program
Project CLEA - educational software used for illustrating modern astronomical techniques
SkyTools - planning software