Below are links to some websites which observers find useful.
Planning Tools:
A Catalog and Atlas of Cataclysmic Variables
http://archive.stsci.edu/prepds/cvcat/index.html [1]
International Supernovae Network
http://www.supernovae.net/isn.htm [2]
Variable Stars Observer - software to help you to plan and log variable stars observations
http://www.astrosurf.com/astropc/varobs/index.html [3]
Obsvar - planning tool which uses AAVSO or AFOEV prediction data and other criteria you specify
http://www.astrosurf.com/lcorp/previsionseng.htm [4]
Other resources:
Guide8 - a full-featured star charting and desktop planetarium program
http://www.projectpluto.com
[5]
Project CLEA - educational software used for illustrating modern astronomical techniques
http://www3.gettysburg.edu/~marschal/clea/CLEAhome.html [6]
SkyTools - planning software
http://www.skyhound.com/ [7]
Links:
[1] http://archive.stsci.edu/prepds/cvcat/index.html
[2] http://www.supernovae.net/isn.htm
[3] http://www.astrosurf.com/astropc/varobs/index.html
[4] http://www.astrosurf.com/lcorp/previsionseng.htm
[5] http://www.projectpluto.com
[6] http://www3.gettysburg.edu/~marschal/clea/CLEAhome.html
[7] http://www.skyhound.com/
[8] http://www.aavso.org/category/tags/observers-useful-links