Center for Backyard Astrophysics
A global network of small telescopes dedicated to photometry of cataclysmic variable stars.
http://cba.phys.columbia.edu/

The Amateur Sky Survey (TASS)
Project objective is to construct low-cost, drift-scan cameras and distribute them to sites around the world to monitor for bright objects across a large section of the sky.
http://www.tass-survey.org/

Spectrashift.com
Site dedicated to amateur radial velocity studies.
http://www.spectrashift.com

The Puckett Observatory
Owned and operated by an amateur astronomer in the North Georgia mountains. Dedicated to the study of comets and the discovery of supernovae.
http://www.cometwatch.com/

Poor Meadow Dyke Observatory, Sky Survey
Provides access to the archived data for this survey of asteroids and variable stars (especially long period variables). Also includes details of the hardware and software, news, tutorials on tracking and using the data, FAQ's and links.
http://www.sky-survey.com